Tid Bits: Oil consumption. It's all in how/where it's consumed.

[Bob Dunahugh]

6 years ago. I knew someone that got very upset that their engine consumed=
one qt every 300 miles. So we looked at the spark plugs. All the spark plu=
gs showed about the same as to discoloration/deposits. The compression test=
came in at reasonable numbers. At 115 to 123 psi. Not great. But not bad. =
Inspection camera showed oil washing around the edges of the pistons. All w=
ashing on all pistons was about the same width. Again. Not a great sign. Bu=
t not bad. Just expected. Put a dial indicating micromotor to the top of ea=
ch rocker arm. Just looking for consistency between all the intake. Then a=
ll the exhaust. Looked good. But that test doesn't show how much the lifter=
s are dished. Or how much of the cam lobes are gone. Again used the inspect=
ion camera to check the cam gear/chain. Had been changed at some past point=
. Warm oil pressures were13psi at idle. 21psi at speed. This is a candidat=
e for a high volume oil pump. But the pump could over load the piston oil c=
ontrol rings. That are already over loaded. Thus it could up oil consumpti=
on. I suggested running it as is. And run a heavier oil. He's been using 20=
W50 oil. Still running well. Oil consumption has been at about 400 miles pe=
r qt. If the engine had all the oil consumption issues in just one or two =
cylinders. That's time for a rebuild. As for what's best for you. Not my mo=
nkeys. Not my circus. Bob Dunahugh

 

[jim kanomata1]

Bob,
What you did saved that unit a rebuilt and gave it more life.
Unless we put on lot of miles, your approach is very great. Thanks for
sharing your experiances.

> 6 years ago. I knew someone that got very upset that their engine
> consumed one qt every 300 miles. So we looked at the spark plugs. All the
> spark plugs showed about the same as to discoloration/deposits. The
> compression test came in at reasonable numbers. At 115 to 123 psi. Not
> great. But not bad. Inspection camera showed oil washing around the edges
> of the pistons. All washing on all pistons was about the same width. Again.
> Not a great sign. But not bad. Just expected. Put a dial indicating
> micromotor to the top of each rocker arm. Just looking for consistency
> between all the intake. Then all the exhaust. Looked good. But that test
> doesn't show how much the lifters are dished. Or how much of the cam lobes
> are gone. Again used the inspection camera to check the cam gear/chain. Had
> been changed at some past point. Warm oil pressures were13psi at idle.
> 21psi at speed. This is a candidate for a high volume oil pump. But the
> pump could over load the piston oil control rings. That are already over
> loaded. Thus it could up oil consumption. I suggested running it as is. And
> run a heavier oil. He's been using 20W50 oil. Still running well. Oil
> consumption has been at about 400 miles per qt. If the engine had all the
> oil consumption issues in just one or two cylinders. That's time for a
> rebuild. As for what's best for you. Not my monkeys. Not my circus. Bob
> Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502

 

[Bob Dunahugh]

Jim K. You picked up on the point perfectly. For some. They just can't affo=
rd a rebuild. This guy doesn't put very many miles on the clock each year. =
He's now going on a seventh year. Bob Dunahugh ___________________=
_____________ From: Bob Dunahugh Sent: Monday, A=
ugust 27, 2018 9:53 PM To: gmclist Subject: Tid Bits: O=
il consumption. It's all in how/where it's consumed. 6 years ago. =
I knew someone that got very upset that their engine consumed one qt every =
300 miles. So we looked at the spark plugs. All the spark plugs showed abou=
t the same as to discoloration/deposits. The compression test came in at re=
asonable numbers. At 115 to 123 psi. Not great. But not bad. Inspection cam=
era showed oil washing around the edges of the pistons. All washing on all =
pistons was about the same width. Again. Not a great sign. But not bad. Jus=
t expected. Put a dial indicating micromotor to the top of each rocker arm.=
Just looking for consistency between all the intake. Then all the exhaust=
. Looked good. But that test doesn't show how much the lifters are dished. =
Or how much of the cam lobes are gone. Again used the inspection camera to =
check the cam gear/chain. Had been changed at some past point. Warm oil pr=
essures were13psi at idle. 21psi at speed. This is a candidate for a high v=
olume oil pump. But the pump could over load the piston oil control rings.=
That are already over loaded. Thus it could up oil consumption. I suggeste=
d running it as is. And run a heavier oil. He's been using 20W50 oil. Still=
running well. Oil consumption has been at about 400 miles per qt. If the e=
ngine had all the oil consumption issues in just one or two cylinders. Tha=
t's time for a rebuild. As for what's best for you. Not my monkeys. Not my =
circus. Bob Dunahugh

 

[sgltrac]

Bob,

If a heavier viscosity oil at operating temp was desired wouldn’t a 30 or
40 weight been better than a 50 ? Or was most of the oil lost when cold?

Sully
Bellevue.

> Bob,
> What you did saved that unit a rebuilt and gave it more life.
> Unless we put on lot of miles, your approach is very great. Thanks for
> sharing your experiances.
>

>
> > 6 years ago. I knew someone that got very upset that their engine
> > consumed one qt every 300 miles. So we looked at the spark plugs. All the
> > spark plugs showed about the same as to discoloration/deposits. The
> > compression test came in at reasonable numbers. At 115 to 123 psi. Not
> > great. But not bad. Inspection camera showed oil washing around the edges
> > of the pistons. All washing on all pistons was about the same width.
> Again.
> > Not a great sign. But not bad. Just expected. Put a dial indicating
> > micromotor to the top of each rocker arm. Just looking for consistency
> > between all the intake. Then all the exhaust. Looked good. But that test
> > doesn't show how much the lifters are dished. Or how much of the cam
> lobes
> > are gone. Again used the inspection camera to check the cam gear/chain.
> Had
> > been changed at some past point. Warm oil pressures were13psi at idle.
> > 21psi at speed. This is a candidate for a high volume oil pump. But the
> > pump could over load the piston oil control rings. That are already over
> > loaded. Thus it could up oil consumption. I suggested running it as is.
> And
> > run a heavier oil. He's been using 20W50 oil. Still running well. Oil
> > consumption has been at about 400 miles per qt. If the engine had all
> the
> > oil consumption issues in just one or two cylinders. That's time for a
> > rebuild. As for what's best for you. Not my monkeys. Not my circus. Bob
> > Dunahugh
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Bob Dunahugh]

Sully. Don't know when most of the oil consumption would occur. Never even =
saw a hint of oil smoke ever. Thought that the 50 might help some. It did. =
Bob Dunahugh ________________________________ From: Bob Dunahugh=
Sent: Monday, August 27, 2018 9:53 PM To: gmcli=
st Subject: Tid Bits: Oil consumption. It's all in how/wh=
ere it's consumed. 6 years ago. I knew someone that got very upset=
that their engine consumed one qt every 300 miles. So we looked at the spa=
rk plugs. All the spark plugs showed about the same as to discoloration/dep=
osits. The compression test came in at reasonable numbers. At 115 to 123 ps=
i. Not great. But not bad. Inspection camera showed oil washing around the =
edges of the pistons. All washing on all pistons was about the same width. =
Again. Not a great sign. But not bad. Just expected. Put a dial indicating =
micromotor to the top of each rocker arm. Just looking for consistency bet=
ween all the intake. Then all the exhaust. Looked good. But that test doesn=
't show how much the lifters are dished. Or how much of the cam lobes are g=
one. Again used the inspection camera to check the cam gear/chain. Had been=
changed at some past point. Warm oil pressures were13psi at idle. 21psi a=
t speed. This is a candidate for a high volume oil pump. But the pump could=
over load the piston oil control rings. That are already over loaded. Thu=
s it could up oil consumption. I suggested running it as is. And run a heav=
ier oil. He's been using 20W50 oil. Still running well. Oil consumption has=
been at about 400 miles per qt. If the engine had all the oil consumption=
issues in just one or two cylinders. That's time for a rebuild. As for wha=
t's best for you. Not my monkeys. Not my circus. Bob Dunahugh

 

[Jim Hupy]

My 403 when I first got it, had 87,000+ miles on the clock. P.O. had been
using 10w - 30 dino oil in the engine. Consumption was 800 or so miles per
quart, which I thought was a bit high. My mechanical fuel pump gasket was
leaking a bit of oil, so I fixed that and cleaned up all the surplus stuff
on the outside of the block. Ran long enough to tell that oil consumption
didn't change much. Darn. So, I decided to change to Valvoline 20w - 50.
Oil consumption changed to a quart every 1200 to 1500 miles. That is where
it is today with over 125,000 miles on the engine. Compression is
consistent at 150 psi across the board. So, the old girl is going to be
driven like she is, until something changes dramatically. Factory says that
a qt per 500 miles is acceptable. I think that borders on excessive
consumption, while the factory is covering their butt on warranty claims.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Sully. Don't know when most of the oil consumption would occur. Never even
> saw a hint of oil smoke ever. Thought that the 50 might help some. It did.
> Bob Dunahugh
>
>
> ________________________________
> From: Bob Dunahugh
> Sent: Monday, August 27, 2018 9:53 PM
> To: gmclist
> Subject: Tid Bits: Oil consumption. It's all in how/where it's consumed.
>
>
> 6 years ago. I knew someone that got very upset that their engine
> consumed one qt every 300 miles. So we looked at the spark plugs. All the
> spark plugs showed about the same as to discoloration/deposits. The
> compression test came in at reasonable numbers. At 115 to 123 psi. Not
> great. But not bad. Inspection camera showed oil washing around the edges
> of the pistons. All washing on all pistons was about the same width. Again.
> Not a great sign. But not bad. Just expected. Put a dial indicating
> micromotor to the top of each rocker arm. Just looking for consistency
> between all the intake. Then all the exhaust. Looked good. But that test
> doesn't show how much the lifters are dished. Or how much of the cam lobes
> are gone. Again used the inspection camera to check the cam gear/chain. Had
> been changed at some past point. Warm oil pressures were13psi at idle.
> 21psi at speed. This is a candidate for a high volume oil pump. But the
> pump could over load the piston oil control rings. That are already over
> loaded. Thus it could up oil consumption. I suggested running it as is. And
> run a heavier oil. He's been using 20W50 oil. Still running well. Oil
> consumption has been at about 400 miles per qt. If the engine had all the
> oil consumption issues in just one or two cylinders. That's time for a
> rebuild. As for what's best for you. Not my monkeys. Not my circus. Bob
> Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[les burt]

Thicker oil generally means a thicker oil film on the cylinder walls. It is my belief that the thicker oil film can overload worn or stuck oil rings, increasing consumption.

I’ve actually seen a few engines where a thinner oil helped reduce oil consumption. Didn’t get to pull them apart for a proper diagnosis, so I can’t say if it was the guides/seals, or rings that were worn.

Thicker oil can also overwhelm the pcv system on engines with excessive blowby. Seen this happen a few times on some worn out engines.

Les Burt
Montreal
'75 Eleganza 26'

>
> My 403 when I first got it, had 87,000+ miles on the clock. P.O. had been
> using 10w - 30 dino oil in the engine. Consumption was 800 or so miles per
> quart, which I thought was a bit high. My mechanical fuel pump gasket was
> leaking a bit of oil, so I fixed that and cleaned up all the surplus stuff
> on the outside of the block. Ran long enough to tell that oil consumption
> didn't change much. Darn. So, I decided to change to Valvoline 20w - 50.
> Oil consumption changed to a quart every 1200 to 1500 miles. That is where
> it is today with over 125,000 miles on the engine. Compression is
> consistent at 150 psi across the board. So, the old girl is going to be
> driven like she is, until something changes dramatically. Factory says that
> a qt per 500 miles is acceptable. I think that borders on excessive
> consumption, while the factory is covering their butt on warranty claims.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>

>>
>> Sully. Don't know when most of the oil consumption would occur. Never even
>> saw a hint of oil smoke ever. Thought that the 50 might help some. It did.
>> Bob Dunahugh
>>
>>
>> ________________________________
>> From: Bob Dunahugh
>> Sent: Monday, August 27, 2018 9:53 PM
>> To: gmclist
>> Subject: Tid Bits: Oil consumption. It's all in how/where it's consumed.
>>
>>
>> 6 years ago. I knew someone that got very upset that their engine
>> consumed one qt every 300 miles. So we looked at the spark plugs. All the
>> spark plugs showed about the same as to discoloration/deposits. The
>> compression test came in at reasonable numbers. At 115 to 123 psi. Not
>> great. But not bad. Inspection camera showed oil washing around the edges
>> of the pistons. All washing on all pistons was about the same width. Again.
>> Not a great sign. But not bad. Just expected. Put a dial indicating
>> micromotor to the top of each rocker arm. Just looking for consistency
>> between all the intake. Then all the exhaust. Looked good. But that test
>> doesn't show how much the lifters are dished. Or how much of the cam lobes
>> are gone. Again used the inspection camera to check the cam gear/chain. Had
>> been changed at some past point. Warm oil pressures were13psi at idle.
>> 21psi at speed. This is a candidate for a high volume oil pump. But the
>> pump could over load the piston oil control rings. That are already over
>> loaded. Thus it could up oil consumption. I suggested running it as is. And
>> run a heavier oil. He's been using 20W50 oil. Still running well. Oil
>> consumption has been at about 400 miles per qt. If the engine had all the
>> oil consumption issues in just one or two cylinders. That's time for a
>> rebuild. As for what's best for you. Not my monkeys. Not my circus. Bob
>> Dunahugh
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Jim Hupy]

My engine has had frequent oil changes and proper maintenance throughout
its service life. It suffers the same problems as many of the motorhomes.
Long periods of inactivity. That is a definite no - no. Better to take
short warmup drives of 20 miles or so every couple of weeks. Keeps
everything lubed, and brakes and all systems operating.
Jim Hupy

> Thicker oil generally means a thicker oil film on the cylinder walls. It
> is my belief that the thicker oil film can overload worn or stuck oil
> rings, increasing consumption.
>
> I’ve actually seen a few engines where a thinner oil helped reduce oil
> consumption. Didn’t get to pull them apart for a proper diagnosis, so I
> can’t say if it was the guides/seals, or rings that were worn.
>
> Thicker oil can also overwhelm the pcv system on engines with excessive
> blowby. Seen this happen a few times on some worn out engines.
>
> Les Burt
> Montreal
> '75 Eleganza 26'
>
>

> >
> > My 403 when I first got it, had 87,000+ miles on the clock. P.O. had been
> > using 10w - 30 dino oil in the engine. Consumption was 800 or so miles
> per
> > quart, which I thought was a bit high. My mechanical fuel pump gasket was
> > leaking a bit of oil, so I fixed that and cleaned up all the surplus
> stuff
> > on the outside of the block. Ran long enough to tell that oil consumption
> > didn't change much. Darn. So, I decided to change to Valvoline 20w - 50.
> > Oil consumption changed to a quart every 1200 to 1500 miles. That is
> where
> > it is today with over 125,000 miles on the engine. Compression is
> > consistent at 150 psi across the board. So, the old girl is going to be
> > driven like she is, until something changes dramatically. Factory says
> that
> > a qt per 500 miles is acceptable. I think that borders on excessive
> > consumption, while the factory is covering their butt on warranty claims.
> > Jim Hupy
> > Salem, Or
> > 78 GMC ROYALE 403
> >
> >> On Wed, Aug 29, 2018, 10:41 AM Bob Dunahugh

> >>
> >> Sully. Don't know when most of the oil consumption would occur. Never
> even
> >> saw a hint of oil smoke ever. Thought that the 50 might help some. It
> did.
> >> Bob Dunahugh
> >>
> >>
> >> ________________________________
> >> From: Bob Dunahugh
> >> Sent: Monday, August 27, 2018 9:53 PM
> >> To: gmclist
> >> Subject: Tid Bits: Oil consumption. It's all in how/where it's consumed.
> >>
> >>
> >> 6 years ago. I knew someone that got very upset that their engine
> >> consumed one qt every 300 miles. So we looked at the spark plugs. All
> the
> >> spark plugs showed about the same as to discoloration/deposits. The
> >> compression test came in at reasonable numbers. At 115 to 123 psi. Not
> >> great. But not bad. Inspection camera showed oil washing around the
> edges
> >> of the pistons. All washing on all pistons was about the same width.
> Again.
> >> Not a great sign. But not bad. Just expected. Put a dial indicating
> >> micromotor to the top of each rocker arm. Just looking for consistency
> >> between all the intake. Then all the exhaust. Looked good. But that test
> >> doesn't show how much the lifters are dished. Or how much of the cam
> lobes
> >> are gone. Again used the inspection camera to check the cam gear/chain.
> Had
> >> been changed at some past point. Warm oil pressures were13psi at idle.
> >> 21psi at speed. This is a candidate for a high volume oil pump. But the
> >> pump could over load the piston oil control rings. That are already
> over
> >> loaded. Thus it could up oil consumption. I suggested running it as is.
> And
> >> run a heavier oil. He's been using 20W50 oil. Still running well. Oil
> >> consumption has been at about 400 miles per qt. If the engine had all
> the
> >> oil consumption issues in just one or two cylinders. That's time for a
> >> rebuild. As for what's best for you. Not my monkeys. Not my circus. Bob
> >> Dunahugh
> >> _______________________________________________
> >> GMCnet mailing list
> >> Unsubscribe or Change List Options:
> >> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >>
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[john phillips]

What does changing the oil weight do the oil pressure? I feel my oil
pressure is low. Would like to have a real gauge. Coach has 117k miles. OP
said it was reabuilt at 100k.

> My engine has had frequent oil changes and proper maintenance throughout
> its service life. It suffers the same problems as many of the motorhomes.
> Long periods of inactivity. That is a definite no - no. Better to take
> short warmup drives of 20 miles or so every couple of weeks. Keeps
> everything lubed, and brakes and all systems operating.
> Jim Hupy
>

>
> > Thicker oil generally means a thicker oil film on the cylinder walls. It
> > is my belief that the thicker oil film can overload worn or stuck oil
> > rings, increasing consumption.
> >
> > I’ve actually seen a few engines where a thinner oil helped reduce oil
> > consumption. Didn’t get to pull them apart for a proper diagnosis, so I
> > can’t say if it was the guides/seals, or rings that were worn.
> >
> > Thicker oil can also overwhelm the pcv system on engines with excessive
> > blowby. Seen this happen a few times on some worn out engines.
> >
> > Les Burt
> > Montreal
> > '75 Eleganza 26'
> >
> >

> > >
> > > My 403 when I first got it, had 87,000+ miles on the clock. P.O. had
> been
> > > using 10w - 30 dino oil in the engine. Consumption was 800 or so miles
> > per
> > > quart, which I thought was a bit high. My mechanical fuel pump gasket
> was
> > > leaking a bit of oil, so I fixed that and cleaned up all the surplus
> > stuff
> > > on the outside of the block. Ran long enough to tell that oil
> consumption
> > > didn't change much. Darn. So, I decided to change to Valvoline 20w -
> 50.
> > > Oil consumption changed to a quart every 1200 to 1500 miles. That is
> > where
> > > it is today with over 125,000 miles on the engine. Compression is
> > > consistent at 150 psi across the board. So, the old girl is going to be
> > > driven like she is, until something changes dramatically. Factory says
> > that
> > > a qt per 500 miles is acceptable. I think that borders on excessive
> > > consumption, while the factory is covering their butt on warranty
> claims.
> > > Jim Hupy
> > > Salem, Or
> > > 78 GMC ROYALE 403
> > >
> > >> On Wed, Aug 29, 2018, 10:41 AM Bob Dunahugh

> > >>
> > >> Sully. Don't know when most of the oil consumption would occur. Never
> > even
> > >> saw a hint of oil smoke ever. Thought that the 50 might help some. It
> > did.
> > >> Bob Dunahugh
> > >>
> > >>
> > >> ________________________________
> > >> From: Bob Dunahugh
> > >> Sent: Monday, August 27, 2018 9:53 PM
> > >> To: gmclist
> > >> Subject: Tid Bits: Oil consumption. It's all in how/where it's
> consumed.
> > >>
> > >>
> > >> 6 years ago. I knew someone that got very upset that their engine
> > >> consumed one qt every 300 miles. So we looked at the spark plugs. All
> > the
> > >> spark plugs showed about the same as to discoloration/deposits. The
> > >> compression test came in at reasonable numbers. At 115 to 123 psi. Not
> > >> great. But not bad. Inspection camera showed oil washing around the
> > edges
> > >> of the pistons. All washing on all pistons was about the same width.
> > Again.
> > >> Not a great sign. But not bad. Just expected. Put a dial indicating
> > >> micromotor to the top of each rocker arm. Just looking for consistency
> > >> between all the intake. Then all the exhaust. Looked good. But that
> test
> > >> doesn't show how much the lifters are dished. Or how much of the cam
> > lobes
> > >> are gone. Again used the inspection camera to check the cam
> gear/chain.
> > Had
> > >> been changed at some past point. Warm oil pressures were13psi at
> idle.
> > >> 21psi at speed. This is a candidate for a high volume oil pump. But
> the
> > >> pump could over load the piston oil control rings. That are already
> > over
> > >> loaded. Thus it could up oil consumption. I suggested running it as
> is.
> > And
> > >> run a heavier oil. He's been using 20W50 oil. Still running well. Oil
> > >> consumption has been at about 400 miles per qt. If the engine had all
> > the
> > >> oil consumption issues in just one or two cylinders. That's time for a
> > >> rebuild. As for what's best for you. Not my monkeys. Not my circus.
> Bob
> > >> Dunahugh
> > >> _______________________________________________
> > >> GMCnet mailing list
> > >> Unsubscribe or Change List Options:
> > >> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> > >>
> > > _______________________________________________
> > > GMCnet mailing list
> > > Unsubscribe or Change List Options:
> > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*

 

[les burt]

If you are concerned that your oil pressure is low, the first thing to do would be to physically verify your engine oil pressure with an accurate mechanical gauge. If that test confirms slightly low oil pressure, you can do as Bob Dunahugh suggested at the beginning of this discussion. Try using a thicker oil such as 20w50. This is normally considered a bandaid to a bigger problem, but if it prolongs having to do a costly engine removal and repair, you are generally ahead.

Les Burt
Montreal
'75 Eleganza 26'

>
> What does changing the oil weight do the oil pressure? I feel my oil
> pressure is low. Would like to have a real gauge. Coach has 117k miles. OP
> said it was reabuilt at 100k.
>
>

>>
>> My engine has had frequent oil changes and proper maintenance throughout
>> its service life. It suffers the same problems as many of the motorhomes.
>> Long periods of inactivity. That is a definite no - no. Better to take
>> short warmup drives of 20 miles or so every couple of weeks. Keeps
>> everything lubed, and brakes and all systems operating.
>> Jim Hupy
>>

>>>
>>> Thicker oil generally means a thicker oil film on the cylinder walls. It
>>> is my belief that the thicker oil film can overload worn or stuck oil
>>> rings, increasing consumption.
>>>
>>> I’ve actually seen a few engines where a thinner oil helped reduce oil
>>> consumption. Didn’t get to pull them apart for a proper diagnosis, so I
>>> can’t say if it was the guides/seals, or rings that were worn.
>>>
>>> Thicker oil can also overwhelm the pcv system on engines with excessive
>>> blowby. Seen this happen a few times on some worn out engines.
>>>
>>> Les Burt
>>> Montreal
>>> '75 Eleganza 26'
>>>
>>>

>>>>
>>>> My 403 when I first got it, had 87,000+ miles on the clock. P.O. had
>> been
>>>> using 10w - 30 dino oil in the engine. Consumption was 800 or so miles
>>> per
>>>> quart, which I thought was a bit high. My mechanical fuel pump gasket
>> was
>>>> leaking a bit of oil, so I fixed that and cleaned up all the surplus
>>> stuff
>>>> on the outside of the block. Ran long enough to tell that oil
>> consumption
>>>> didn't change much. Darn. So, I decided to change to Valvoline 20w -
>> 50.
>>>> Oil consumption changed to a quart every 1200 to 1500 miles. That is
>>> where
>>>> it is today with over 125,000 miles on the engine. Compression is
>>>> consistent at 150 psi across the board. So, the old girl is going to be
>>>> driven like she is, until something changes dramatically. Factory says
>>> that
>>>> a qt per 500 miles is acceptable. I think that borders on excessive
>>>> consumption, while the factory is covering their butt on warranty
>> claims.
>>>> Jim Hupy
>>>> Salem, Or
>>>> 78 GMC ROYALE 403
>>>>
>>>>> On Wed, Aug 29, 2018, 10:41 AM Bob Dunahugh

>>>>>
>>>>> Sully. Don't know when most of the oil consumption would occur. Never
>>> even
>>>>> saw a hint of oil smoke ever. Thought that the 50 might help some. It
>>> did.
>>>>> Bob Dunahugh
>>>>>
>>>>>
>>>>> ________________________________
>>>>> From: Bob Dunahugh
>>>>> Sent: Monday, August 27, 2018 9:53 PM
>>>>> To: gmclist
>>>>> Subject: Tid Bits: Oil consumption. It's all in how/where it's
>> consumed.
>>>>>
>>>>>
>>>>> 6 years ago. I knew someone that got very upset that their engine
>>>>> consumed one qt every 300 miles. So we looked at the spark plugs. All
>>> the
>>>>> spark plugs showed about the same as to discoloration/deposits. The
>>>>> compression test came in at reasonable numbers. At 115 to 123 psi. Not
>>>>> great. But not bad. Inspection camera showed oil washing around the
>>> edges
>>>>> of the pistons. All washing on all pistons was about the same width.
>>> Again.
>>>>> Not a great sign. But not bad. Just expected. Put a dial indicating
>>>>> micromotor to the top of each rocker arm. Just looking for consistency
>>>>> between all the intake. Then all the exhaust. Looked good. But that
>> test
>>>>> doesn't show how much the lifters are dished. Or how much of the cam
>>> lobes
>>>>> are gone. Again used the inspection camera to check the cam
>> gear/chain.
>>> Had
>>>>> been changed at some past point. Warm oil pressures were13psi at
>> idle.
>>>>> 21psi at speed. This is a candidate for a high volume oil pump. But
>> the
>>>>> pump could over load the piston oil control rings. That are already
>>> over
>>>>> loaded. Thus it could up oil consumption. I suggested running it as
>> is.
>>> And
>>>>> run a heavier oil. He's been using 20W50 oil. Still running well. Oil
>>>>> consumption has been at about 400 miles per qt. If the engine had all
>>> the
>>>>> oil consumption issues in just one or two cylinders. That's time for a
>>>>> rebuild. As for what's best for you. Not my monkeys. Not my circus.
>> Bob
>>>>> Dunahugh
>>>>> _______________________________________________
>>>>> GMCnet mailing list
>>>>> Unsubscribe or Change List Options:
>>>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>>>
>>>> _______________________________________________
>>>> GMCnet mailing list
>>>> Unsubscribe or Change List Options:
>>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
> --
>
> *John Phillips*
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Rdenney]

On my old engine, I was getting about 15 psi at idle, and 30 or so at
speed. The engine had an uncertain history (valve covers were painted
black) and 90k+ miles, and I switched to Mobil1 High Mileage 15W-50.
Pressure was 20 at idle and 35-40 at speed after that. Which is plenty. But
I didn’t make that change to get higher pressure, I did it to get a
stronger oil film in looser bearings.

Dick P once said that NASCAR racers can run all day at 30 psi and 8000
RPMs. Pressure is not what we need—an ever-present film is what we need.
The problem with worn tolerances is not so much that they relieve pressure,
but that they leak a lot of oil. A high-volume pump prevents those leaks
from causing starvation somewhere else.

Do we need it? Certainly not for a tight engine. But I don’t worship at the
altar of GM engineering, either. They did as much cost engineering,
fuel-consumption engineering, and emissions engineering as they did
durability engineering. Their engines were tight not because they made the
parts fit (as we expect to do during a rebuild), but that they selected
parts with the right dimensions for the assembly task at hand. As I
understand it, parts were sorted across their manufacturing tolerance range
and the selected on the line as needed. They were auto workers, not
artists.

Rick “who uses a mechanical oil pressure gauge” Denney

On Thu, Aug 30, 2018 at 12:48 AM John Phillips
wrote:

> What does changing the oil weight do the oil pressure? I feel my oil
> pressure is low. Would like to have a real gauge. Coach has 117k miles. OP
> said it was reabuilt at 100k.
>
> --
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com

 

[Jim Hupy]

You guys need to listen to the guy that represents AM General ( they make
the Hummer, both civilian and military versions) When they bought the
production rights to the Hummer from GM, they bought the engine
manufacturing production line, tooling, everything but the actual foundry
where iron castings were produced. They did acquire a bunch of bare engine
blocks, and when they set up the production line, they found out why GM got
rid of the Hummer. High graphite content in the cast iron led to long
tooling life, but crappy strength and durability in the engines. Threaded
holes pulled out in service, lost their clamping ability, led to Internal
coolant and combustion leak failures, short engine life, etc.
When AM General switched to high nickel content in their new block
castings, the used tooling that GM sold them failed quickly. Leaving AM
General in a pickle. A few band aid fixes were tried, and failed.
AM General bit the bullet, and did a total redesign of the 6.5 Diesel.
That included castings, tooling, production machines, durability testing,
the whole deal.
The 6.5 that they build today is the same displacement as the GM built
one, and that is about all they have in common.
AM General spent BILLIONS fixing the shortcomings. So, the product
development processes that GM used on our Olds engines in the 60's and
early 70's, disappeared, and brought us products like Volera, Saturn,
Fiero, Astro, to name a few. That led to the demise of Saturn, Pontiac,
Oldsmobile, and a huge government bailout of what was left. Better? Not in
my world.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> On my old engine, I was getting about 15 psi at idle, and 30 or so at
> speed. The engine had an uncertain history (valve covers were painted
> black) and 90k+ miles, and I switched to Mobil1 High Mileage 15W-50.
> Pressure was 20 at idle and 35-40 at speed after that. Which is plenty. But
> I didn’t make that change to get higher pressure, I did it to get a
> stronger oil film in looser bearings.
>
> Dick P once said that NASCAR racers can run all day at 30 psi and 8000
> RPMs. Pressure is not what we need—an ever-present film is what we need.
> The problem with worn tolerances is not so much that they relieve pressure,
> but that they leak a lot of oil. A high-volume pump prevents those leaks
> from causing starvation somewhere else.
>
> Do we need it? Certainly not for a tight engine. But I don’t worship at the
> altar of GM engineering, either. They did as much cost engineering,
> fuel-consumption engineering, and emissions engineering as they did
> durability engineering. Their engines were tight not because they made the
> parts fit (as we expect to do during a rebuild), but that they selected
> parts with the right dimensions for the assembly task at hand. As I
> understand it, parts were sorted across their manufacturing tolerance range
> and the selected on the line as needed. They were auto workers, not
> artists.
>
> Rick “who uses a mechanical oil pressure gauge” Denney
>
> On Thu, Aug 30, 2018 at 12:48 AM John Phillips

>
> > What does changing the oil weight do the oil pressure? I feel my oil
> > pressure is low. Would like to have a real gauge. Coach has 117k miles.
> OP
> > said it was reabuilt at 100k.
> >
> > --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[jim kanomata1]

What I learn from this discuassion is that a higher viscosity does not
always cut down on consumption.
Also keep in mind about Overfilling the unit.
Keep in mind that there is a quart of oil sitting in the front part of the
pan, so one need to consider it and try running one quart low and see if
that can help as well.

> You guys need to listen to the guy that represents AM General ( they make
> the Hummer, both civilian and military versions) When they bought the
> production rights to the Hummer from GM, they bought the engine
> manufacturing production line, tooling, everything but the actual foundry
> where iron castings were produced. They did acquire a bunch of bare engine
> blocks, and when they set up the production line, they found out why GM got
> rid of the Hummer. High graphite content in the cast iron led to long
> tooling life, but crappy strength and durability in the engines. Threaded
> holes pulled out in service, lost their clamping ability, led to Internal
> coolant and combustion leak failures, short engine life, etc.
> When AM General switched to high nickel content in their new block
> castings, the used tooling that GM sold them failed quickly. Leaving AM
> General in a pickle. A few band aid fixes were tried, and failed.
> AM General bit the bullet, and did a total redesign of the 6.5 Diesel.
> That included castings, tooling, production machines, durability testing,
> the whole deal.
> The 6.5 that they build today is the same displacement as the GM built
> one, and that is about all they have in common.
> AM General spent BILLIONS fixing the shortcomings. So, the product
> development processes that GM used on our Olds engines in the 60's and
> early 70's, disappeared, and brought us products like Volera, Saturn,
> Fiero, Astro, to name a few. That led to the demise of Saturn, Pontiac,
> Oldsmobile, and a huge government bailout of what was left. Better? Not in
> my world.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>

>
> > On my old engine, I was getting about 15 psi at idle, and 30 or so at
> > speed. The engine had an uncertain history (valve covers were painted
> > black) and 90k+ miles, and I switched to Mobil1 High Mileage 15W-50.
> > Pressure was 20 at idle and 35-40 at speed after that. Which is plenty.
> But
> > I didn’t make that change to get higher pressure, I did it to get a
> > stronger oil film in looser bearings.
> >
> > Dick P once said that NASCAR racers can run all day at 30 psi and 8000
> > RPMs. Pressure is not what we need—an ever-present film is what we need.
> > The problem with worn tolerances is not so much that they relieve
> pressure,
> > but that they leak a lot of oil. A high-volume pump prevents those leaks
> > from causing starvation somewhere else.
> >
> > Do we need it? Certainly not for a tight engine. But I don’t worship at
> the
> > altar of GM engineering, either. They did as much cost engineering,
> > fuel-consumption engineering, and emissions engineering as they did
> > durability engineering. Their engines were tight not because they made
> the
> > parts fit (as we expect to do during a rebuild), but that they selected
> > parts with the right dimensions for the assembly task at hand. As I
> > understand it, parts were sorted across their manufacturing tolerance
> range
> > and the selected on the line as needed. They were auto workers, not
> > artists.
> >
> > Rick “who uses a mechanical oil pressure gauge” Denney
> >
> > On Thu, Aug 30, 2018 at 12:48 AM John Phillips >

> >
> > > What does changing the oil weight do the oil pressure? I feel my oil
> > > pressure is low. Would like to have a real gauge. Coach has 117k miles.
> > OP
> > > said it was reabuilt at 100k.
> > >
> > > --
> > Rick Denney
> > 73 x-Glacier 230 "Jaws"
> > Off-list email to rick at rickdenney dot com
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502

 

[Irish Rogue]

Jim H:
Very interesting - thanks for the history lesson!
Mike/The Corvair a holic

Sent from my iPhone

>
> You guys need to listen to the guy that represents AM General ( they make
> the Hummer, both civilian and military versions) When they bought the
> production rights to the Hummer from GM, they bought the engine
> manufacturing production line, tooling, everything but the actual foundry
> where iron castings were produced. They did acquire a bunch of bare engine
> blocks, and when they set up the production line, they found out why GM got
> rid of the Hummer. High graphite content in the cast iron led to long
> tooling life, but crappy strength and durability in the engines. Threaded
> holes pulled out in service, lost their clamping ability, led to Internal
> coolant and combustion leak failures, short engine life, etc.
> When AM General switched to high nickel content in their new block
> castings, the used tooling that GM sold them failed quickly. Leaving AM
> General in a pickle. A few band aid fixes were tried, and failed.
> AM General bit the bullet, and did a total redesign of the 6.5 Diesel.
> That included castings, tooling, production machines, durability testing,
> the whole deal.
> The 6.5 that they build today is the same displacement as the GM built
> one, and that is about all they have in common.
> AM General spent BILLIONS fixing the shortcomings. So, the product
> development processes that GM used on our Olds engines in the 60's and
> early 70's, disappeared, and brought us products like Volera, Saturn,
> Fiero, Astro, to name a few. That led to the demise of Saturn, Pontiac,
> Oldsmobile, and a huge government bailout of what was left. Better? Not in
> my world.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>

>>
>> On my old engine, I was getting about 15 psi at idle, and 30 or so at
>> speed. The engine had an uncertain history (valve covers were painted
>> black) and 90k+ miles, and I switched to Mobil1 High Mileage 15W-50.
>> Pressure was 20 at idle and 35-40 at speed after that. Which is plenty. But
>> I didn’t make that change to get higher pressure, I did it to get a
>> stronger oil film in looser bearings.
>>
>> Dick P once said that NASCAR racers can run all day at 30 psi and 8000
>> RPMs. Pressure is not what we need—an ever-present film is what we need.
>> The problem with worn tolerances is not so much that they relieve pressure,
>> but that they leak a lot of oil. A high-volume pump prevents those leaks
>> from causing starvation somewhere else.
>>
>> Do we need it? Certainly not for a tight engine. But I don’t worship at the
>> altar of GM engineering, either. They did as much cost engineering,
>> fuel-consumption engineering, and emissions engineering as they did
>> durability engineering. Their engines were tight not because they made the
>> parts fit (as we expect to do during a rebuild), but that they selected
>> parts with the right dimensions for the assembly task at hand. As I
>> understand it, parts were sorted across their manufacturing tolerance range
>> and the selected on the line as needed. They were auto workers, not
>> artists.
>>
>> Rick “who uses a mechanical oil pressure gauge” Denney
>>
>> On Thu, Aug 30, 2018 at 12:48 AM John Phillips

>>
>>> What does changing the oil weight do the oil pressure? I feel my oil
>>> pressure is low. Would like to have a real gauge. Coach has 117k miles.
>> OP
>>> said it was reabuilt at 100k.
>>>
>>> --
>> Rick Denney
>> 73 x-Glacier 230 "Jaws"
>> Off-list email to rick at rickdenney dot com
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Matt Colie]

> What I learn from this discussion is that a higher viscosity does not always cut down on consumption.
> Also keep in mind about Overfilling the unit.
> Keep in mind that there is a quart of oil sitting in the front part of the pan, so one need to consider it and try running one quart low and see
> if
> that can help as well.

This has all been good and there is very little that a guy that was a dynolab rat for several decades will disagree with at all.

I can tell you from a recent excursion though my very own 455 (461) that if it had not suffered an unpredictable material failure, I would never have
even removed a cylinder head cover. Those engines were built to last. It is no wonder that they were used in so many industrial services.

Chaumière had a sudden change from 2000+ miles per quart to -500 miles per quart and a lot of that was getting into the air filter. This demanded
attention. If I was to loose and engine this good for a lack of care, that would be an unforgivable act.

Matt - and he now has a fine running coach again

The 2K mile was a pleasant surprise. I had been filling the crankcase to the full mark on the stick. Then, I made a mistake and did not have the
make-up lube oil aboard that I thought I did. We were not far from home, so I guessed we would be at the 1/2 below add when we were back at home
port. I was wrong. When I checked next, she was still just 1 down. So, we ran more, (I did replace the make-up oil onboard) and the lube oil stayed
at that one down mark. That is where I ran her for the next 60k miles.

If you do not know this, here it is...
Lubricating oil has many functions in a modern internal combustion engine:
1 - Cooling of both working surfaces and parts exposed to combustion heat.
2 - Working fluid for chain tensioners and lash adjusters (what lifter really are).
3 - System flushing to remove both wear debris and combustion by products.
4 - Motion damping to prevent the parts with clearance from impacting each other.
5 - Serve as the wedge element of the hydraulic bearings.
6 - To provide the film between metal parts to prevent damage. (What most people think of as lubrication.)

If you think about this list (it is presented here is nominal importance), you will understand that neither lube system pressure or the actual dynamic
viscosity matter very much. This is why splash lube works at low specific output.

And for those that care, the Melling M-22FHV is only about 20~25% more displacement than the standard M-22F. The M-22F pump is very much like the
stock lube oil pumps that I had recently saw. I looked at my assembly and measurement data and thought it was a good idea.
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[Jim Hupy]

When we talk about pressure vs splash systems. They are 6 of 1, a half
dozen of another.
The trick is in getting the proper amount of the correct temperature
and viscosity lube oil to the moving parts at the correct time on the load
cycle of the engine.
Separation of moving parts in running engines does NOT come from oil
pressure as produced by an oil pump. It is developed in clearance spaces by
the differing speeds of the moving parts as both are coated by a
microscopic layer of oil. Something called a "fluid wedge" is created.
THAT, depending upon available space, forces the two surfaces apart and
prevents metal to metal contact. Factors involved are quite a few, but
several are, clearance space, temperature, volume of oil, speed of moving
parts, viscosity and shear resistance of the oil, etc.
I did not invent this in my head. It is well known by oil companies,
engineers, auto manufacturers. And is more complex than I have described
here. Better discussed over adult beverages.
Jim Hupy
Salem, Or

> > What I learn from this discussion is that a higher viscosity does not
> always cut down on consumption.
> > Also keep in mind about Overfilling the unit.
> > Keep in mind that there is a quart of oil sitting in the front part of
> the pan, so one need to consider it and try running one quart low and see
> > if
> > that can help as well.
>
> This has all been good and there is very little that a guy that was a
> dynolab rat for several decades will disagree with at all.
>
> I can tell you from a recent excursion though my very own 455 (461) that
> if it had not suffered an unpredictable material failure, I would never have
> even removed a cylinder head cover. Those engines were built to last. It
> is no wonder that they were used in so many industrial services.
>
> Chaumière had a sudden change from 2000+ miles per quart to -500 miles per
> quart and a lot of that was getting into the air filter. This demanded
> attention. If I was to loose and engine this good for a lack of care,
> that would be an unforgivable act.
>
> Matt - and he now has a fine running coach again
>
> The 2K mile was a pleasant surprise. I had been filling the crankcase to
> the full mark on the stick. Then, I made a mistake and did not have the
> make-up lube oil aboard that I thought I did. We were not far from home,
> so I guessed we would be at the 1/2 below add when we were back at home
> port. I was wrong. When I checked next, she was still just 1 down. So,
> we ran more, (I did replace the make-up oil onboard) and the lube oil stayed
> at that one down mark. That is where I ran her for the next 60k miles.
>
> If you do not know this, here it is...
> Lubricating oil has many functions in a modern internal combustion engine:
> 1 - Cooling of both working surfaces and parts exposed to combustion heat.
> 2 - Working fluid for chain tensioners and lash adjusters (what lifter
> really are).
> 3 - System flushing to remove both wear debris and combustion by products.
> 4 - Motion damping to prevent the parts with clearance from impacting each
> other.
> 5 - Serve as the wedge element of the hydraulic bearings.
> 6 - To provide the film between metal parts to prevent damage. (What most
> people think of as lubrication.)
>
> If you think about this list (it is presented here is nominal importance),
> you will understand that neither lube system pressure or the actual dynamic
> viscosity matter very much. This is why splash lube works at low specific
> output.
>
> And for those that care, the Melling M-22FHV is only about 20~25% more
> displacement than the standard M-22F. The M-22F pump is very much like the
> stock lube oil pumps that I had recently saw. I looked at my assembly and
> measurement data and thought it was a good idea.
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Bob Dunahugh]

Owners get WAY to wrapped up in oil pressure readings. My race engines can=
run in the 7 to 8,000 RPM range at 25 PSI all day. 12.4 to 1 compression r=
atios. 110 octane leaded fuel. ( at 6.50 a gallon. Then just 3 miles to tha=
t gallon. And you thought our GMC's cost a lot per mile ) That's serious s=
tress on parts. Our GMC's are at 8 to 1 as a reference . My race engine i=
dle oil pressure can get down to 12 to 16 PSI. I want my HP/torque going to=
the wheels. Not going to the oil pump. So it can put higher dumb numbers =
on a gauge. As to your GMC. 10 psi at idle. 20 at speed are both at the low=
end. But fine. Then remember to avoid lugging. Put some 20/50 dino oil in=
. The oil is just a little thicker. Changer your oil/filter every 2,000 mil=
es. Our engines were dirty engines when new. They need frequent oil/filter =
changes more the expensive oils. Bob Dunahugh ____________________=
____________ From: Bob Dunahugh Sent: Wednesday,=
August 29, 2018 12:40 PM To: gmclist Subject: RE:Tid B=
its: Oil consumption. It's all in how/where it's consumed. Sully. D=
on't know when most of the oil consumption would occur. Never even saw a hi=
nt of oil smoke ever. Thought that the 50 might help some. It did. Bob Dun=
ahugh ________________________________ From: Bob Dunahugh Sent: Monday, August 27, 2018 9:53 PM To: gmclist=
gmcnet.org Subject: Tid Bits: Oil consumption. It's all in how/where it's=
consumed. 6 years ago. I knew someone that got very upset that th=
eir engine consumed one qt every 300 miles. So we looked at the spark plugs=
. All the spark plugs showed about the same as to discoloration/deposits. T=
he compression test came in at reasonable numbers. At 115 to 123 psi. Not g=
reat. But not bad. Inspection camera showed oil washing around the edges of=
the pistons. All washing on all pistons was about the same width. Again. N=
ot a great sign. But not bad. Just expected. Put a dial indicating micromot=
or to the top of each rocker arm. Just looking for consistency between all=
the intake. Then all the exhaust. Looked good. But that test doesn't show =
how much the lifters are dished. Or how much of the cam lobes are gone. Aga=
in used the inspection camera to check the cam gear/chain. Had been changed=
at some past point. Warm oil pressures were13psi at idle. 21psi at speed.=
This is a candidate for a high volume oil pump. But the pump could over lo=
ad the piston oil control rings. That are already over loaded. Thus it cou=
ld up oil consumption. I suggested running it as is. And run a heavier oil.=
He's been using 20W50 oil. Still running well. Oil consumption has been at=
about 400 miles per qt. If the engine had all the oil consumption issues =
in just one or two cylinders. That's time for a rebuild. As for what's best=
for you. Not my monkeys. Not my circus. Bob Dunahugh

 

[john r. lebetski]

If I remember correctly, Dick P does not recommend anything over 40 weight hot rating. 50 weight makes you think things are better as the gauge is
pretty, but in reality less oil is getting to
Engine parts as the bypass valve is open a greater % of the time. That oil gets pumped (waisting power) then released via the bypass to the pump inlet
area. This is especially important in the cooling task job the oil has to do. The more fluid passing over a heat exchanger (engine parts) the more
calories that can be transfered.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[d c *mac* macdonald]

And these NEW engines from AM General are supposedly what Jim Bounds is going to be using in his diesel conversions of the GMC motorhomes.

D C "Mac" Macdonald​
Amateur Radio K2GKK​
Since 30 November '53​
USAF and FAA, Retired​
Member GMCMI & Classics​
Oklahoma City, OK​
"The Money Pit"​
TZE166V101966​
'76 ex-Palm Beach​
k2gkk + hotmail dot com​

________________________________
From: Gmclist on behalf of James Hupy
Sent: Thursday, August 30, 2018 09:32
To: gmclist
Subject: Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed.

You guys need to listen to the guy that represents AM General ( they make
the Hummer, both civilian and military versions) When they bought the
production rights to the Hummer from GM, they bought the engine
manufacturing production line, tooling, everything but the actual foundry
where iron castings were produced. They did acquire a bunch of bare engine
blocks, and when they set up the production line, they found out why GM got
rid of the Hummer. High graphite content in the cast iron led to long
tooling life, but crappy strength and durability in the engines. Threaded
holes pulled out in service, lost their clamping ability, led to Internal
coolant and combustion leak failures, short engine life, etc.
When AM General switched to high nickel content in their new block
castings, the used tooling that GM sold them failed quickly. Leaving AM
General in a pickle. A few band aid fixes were tried, and failed.
AM General bit the bullet, and did a total redesign of the 6.5 Diesel.
That included castings, tooling, production machines, durability testing,
the whole deal.
The 6.5 that they build today is the same displacement as the GM built
one, and that is about all they have in common.
AM General spent BILLIONS fixing the shortcomings. So, the product
development processes that GM used on our Olds engines in the 60's and
early 70's, disappeared, and brought us products like Volera, Saturn,
Fiero, Astro, to name a few. That led to the demise of Saturn, Pontiac,
Oldsmobile, and a huge government bailout of what was left. Better? Not in
my world.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> On my old engine, I was getting about 15 psi at idle, and 30 or so at
> speed. The engine had an uncertain history (valve covers were painted
> black) and 90k+ miles, and I switched to Mobil1 High Mileage 15W-50.
> Pressure was 20 at idle and 35-40 at speed after that. Which is plenty. But
> I didn’t make that change to get higher pressure, I did it to get a
> stronger oil film in looser bearings.
>
> Dick P once said that NASCAR racers can run all day at 30 psi and 8000
> RPMs. Pressure is not what we need—an ever-present film is what we need.
> The problem with worn tolerances is not so much that they relieve pressure,
> but that they leak a lot of oil. A high-volume pump prevents those leaks
> from causing starvation somewhere else.
>
> Do we need it? Certainly not for a tight engine. But I don’t worship at the
> altar of GM engineering, either. They did as much cost engineering,
> fuel-consumption engineering, and emissions engineering as they did
> durability engineering. Their engines were tight not because they made the
> parts fit (as we expect to do during a rebuild), but that they selected
> parts with the right dimensions for the assembly task at hand. As I
> understand it, parts were sorted across their manufacturing tolerance range
> and the selected on the line as needed. They were auto workers, not
> artists.
>
> Rick “who uses a mechanical oil pressure gauge” Denney
>
> On Thu, Aug 30, 2018 at 12:48 AM John Phillips

>
> > What does changing the oil weight do the oil pressure? I feel my oil
> > pressure is low. Would like to have a real gauge. Coach has 117k miles.
> OP
> > said it was reabuilt at 100k.
> >
> > --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
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[Jim Hupy]

That information that I passed on about AM General came from a conversation
between the AM General Rep, Manny T. and myself, along with several others
at a GMCWS rally where Manny presented an engine transmission package
presentation for our GMC coaches. That was several years ago at Frenchglen,
California.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> And these NEW engines from AM General are supposedly what Jim Bounds is
> going to be using in his diesel conversions of the GMC motorhomes.
>
> D C "Mac" Macdonald​
> Amateur Radio K2GKK​
> Since 30 November '53​
> USAF and FAA, Retired​
> Member GMCMI & Classics​
> Oklahoma City, OK​
> "The Money Pit"​
> TZE166V101966​
> '76 ex-Palm Beach​
> k2gkk + hotmail dot com​
>
> ________________________________
> From: Gmclist on behalf of James Hupy <
> jamesh1296>
> Sent: Thursday, August 30, 2018 09:32
> To: gmclist
> Subject: Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where
> it's consumed.
>
> You guys need to listen to the guy that represents AM General ( they make
> the Hummer, both civilian and military versions) When they bought the
> production rights to the Hummer from GM, they bought the engine
> manufacturing production line, tooling, everything but the actual foundry
> where iron castings were produced. They did acquire a bunch of bare engine
> blocks, and when they set up the production line, they found out why GM got
> rid of the Hummer. High graphite content in the cast iron led to long
> tooling life, but crappy strength and durability in the engines. Threaded
> holes pulled out in service, lost their clamping ability, led to Internal
> coolant and combustion leak failures, short engine life, etc.
> When AM General switched to high nickel content in their new block
> castings, the used tooling that GM sold them failed quickly. Leaving AM
> General in a pickle. A few band aid fixes were tried, and failed.
> AM General bit the bullet, and did a total redesign of the 6.5 Diesel.
> That included castings, tooling, production machines, durability testing,
> the whole deal.
> The 6.5 that they build today is the same displacement as the GM built
> one, and that is about all they have in common.
> AM General spent BILLIONS fixing the shortcomings. So, the product
> development processes that GM used on our Olds engines in the 60's and
> early 70's, disappeared, and brought us products like Volera, Saturn,
> Fiero, Astro, to name a few. That led to the demise of Saturn, Pontiac,
> Oldsmobile, and a huge government bailout of what was left. Better? Not in
> my world.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>

>
> > On my old engine, I was getting about 15 psi at idle, and 30 or so at
> > speed. The engine had an uncertain history (valve covers were painted
> > black) and 90k+ miles, and I switched to Mobil1 High Mileage 15W-50.
> > Pressure was 20 at idle and 35-40 at speed after that. Which is plenty.
> But
> > I didn’t make that change to get higher pressure, I did it to get a
> > stronger oil film in looser bearings.
> >
> > Dick P once said that NASCAR racers can run all day at 30 psi and 8000
> > RPMs. Pressure is not what we need—an ever-present film is what we need.
> > The problem with worn tolerances is not so much that they relieve
> pressure,
> > but that they leak a lot of oil. A high-volume pump prevents those leaks
> > from causing starvation somewhere else.
> >
> > Do we need it? Certainly not for a tight engine. But I don’t worship at
> the
> > altar of GM engineering, either. They did as much cost engineering,
> > fuel-consumption engineering, and emissions engineering as they did
> > durability engineering. Their engines were tight not because they made
> the
> > parts fit (as we expect to do during a rebuild), but that they selected
> > parts with the right dimensions for the assembly task at hand. As I
> > understand it, parts were sorted across their manufacturing tolerance
> range
> > and the selected on the line as needed. They were auto workers, not
> > artists.
> >
> > Rick “who uses a mechanical oil pressure gauge” Denney
> >
> > On Thu, Aug 30, 2018 at 12:48 AM John Phillips >

> >
> > > What does changing the oil weight do the oil pressure? I feel my oil
> > > pressure is low. Would like to have a real gauge. Coach has 117k miles.
> > OP
> > > said it was reabuilt at 100k.
> > >
> > > --
> > Rick Denney
> > 73 x-Glacier 230 "Jaws"
> > Off-list email to rick at rickdenney dot com
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> >
> https://nam03.safelinks.protection.outlook.com/?url=http%3A%2F%2Flist.gmcnet.org%2Fmailman%2Flistinfo%2Fgmclist_list.gmcnet.org&data=02%7C01%7C%7Cd38593c67fc944ed6fbd08d60e85508e%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636712363067808201&sdata=rpHdDekC6D9p8%2BQ9xdB69%2BdwFLaYzuwkQMpbrHre778%3D&reserved=0
> >
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