Oil change question (gasp!)

[justin brady1]

Hey guys,
So on our 5k trip we had a pretty good oil leak that I fixed 1/4 of the way through. That slowed consumption a lot.
I still had some oil consumption though. I had to add roughly a 1/2 quart or so every 500 miles which seemed excessive, but everything runs great, no
smoke.

Today I changed the oil for the first time since the trip and u followed the recommendations for quite a few around here and put 5 qts in instead of
6. At 5 qts the dipstick reads just a bit under the "add" line, which coincidentally is where it seemed to end up after a bunch of miles without
adding oil.

I suspect that the dipstick is wrong and I've been overfilling it and it burned it off, only for me to overfill it again etc.

So should I make a new mark on the dipstick or just keep track of it from?
--
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455

 

[Jim Hupy]

Justin, if your coach is level, and you change the filter, you should take
6 quarts of oil to change on a 455 with stock filter and cooler and oil
pan. To verify dipstick, drain until just a few drips are coming out of a
warm engine. Replace the oil filter. Pour in 5 quarts of oil. Let it set
for 5 minutes or so, then check your oil. I should read 1 qt. low. If not,
your dipstick is inaccurate. Add 1 qt., run the engine for long enough to
refill the filter, then recheck. It should now read full. It is what I
would do.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Hey guys,
> So on our 5k trip we had a pretty good oil leak that I fixed 1/4 of the
> way through. That slowed consumption a lot.
> I still had some oil consumption though. I had to add roughly a 1/2 quart
> or so every 500 miles which seemed excessive, but everything runs great, no
> smoke.
>
> Today I changed the oil for the first time since the trip and u followed
> the recommendations for quite a few around here and put 5 qts in instead of
> 6. At 5 qts the dipstick reads just a bit under the "add" line, which
> coincidentally is where it seemed to end up after a bunch of miles without
> adding oil.
>
> I suspect that the dipstick is wrong and I've been overfilling it and it
> burned it off, only for me to overfill it again etc.
>
> So should I make a new mark on the dipstick or just keep track of it from?
> --
> Justin Brady
> http://www.thegmcrv.com/
> 1976 Palm Beach 455
>
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[Matt Colie]

> Hey guys,
> So on our 5k trip we had a pretty good oil leak that I fixed 1/4 of the way through. That slowed consumption a lot.
> I still had some oil consumption though. I had to add roughly a 1/2 quart or so every 500 miles which seemed excessive, but everything runs
> great, no smoke.
>
> Today I changed the oil for the first time since the trip and I followed the recommendations of quite a few around here and put 5 qts in instead
> of 6. At 5 qts the dipstick reads just a bit under the "add" line, which coincidentally is where it seemed to end up after a bunch of miles without
> adding oil.
>
> I suspect that the dipstick is wrong and I've been overfilling it and it burned it off, only for me to overfill it again etc.
>
> So should I make a new mark on the dipstick or just keep track of it from here?

Justin,

While Jim is technically correct, I have monitoring pressure, temperature and having oil analyzed for the last 60k miles.

When I first got the coach, I kept the lube oil level at or above the full mark and rarely did better than 500m/qt. Then we took off without
refilling the makeup oil inventory. At 500 mile she was at the add mark. we were another 250 from the barn so I ran it. When next checked is was
just the other side of the "Add" line. So, I refilled the carried inventory and not the main engine. Another 250 miles and now it was 1/8 below
"Add", so I brought it back up to "Add". In the final tally, when running at the "Add" mark, the lube oil consumption was about 2000m/qt. That is
where it has been for the last 50,000 miles.

Knowing OEs as I do, I suspect that the "Full" mark was copied from the passcar version that runs with way lower cylinder pressures and therefore less
blow-by. This is why the coach has different valve gear covers.

While I am planning to have the engine out and open this winter, it is because my reports say that there is coolant in the lube oil and that is bad. I
would hate to loose an engine that has been this good just for a small lack of attention.

Matt
--
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

 

[justin brady1]

Matt,
I've read a lot of similar stories.
I think I'm going to run it as is with 5qts and keep a close eye on consumption and check often to make sure it doesn't get low.
--
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455

 

[justin brady1]

Matt,
I've read a lot of similar stories.
I think I'm going to run it as is with 5qts and keep a close eye on consumption and check often to make sure it doesn't get low.
--
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455

 

[Ken H.]

Justin,

If you want to really understand the oil level, check this album:

http://www.gmcmhphotos.com/photos/g3942-455-oil-pan-capacity.html

My conclusion from all that was that the 6 quarts is probably right for a
new/rebuilt engine, but subsequent oil & filter changes only call for 5
quarts, with any above that just being quickly burned or blown out. It's
obvious from those photos that oil's got to be VERY low before the engine
is starved -- that's not to say a full dose isn't needed for cooling, etc.

Ken H.

> Matt,
> I've read a lot of similar stories.
> I think I'm going to run it as is with 5qts and keep a close eye on
> consumption and check often to make sure it doesn't get low.
> --

 

[justin brady1]

Thanks for the thorough photos Ken!

--
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455

 

[Ken B]

If you were to drain the front of the oil pan, which you can not do without drilling a hole in the pan and were to drain the oil lines and cooler,
then it will take 6 quarts to refill then engine and filter. When I change my oil, 5 quarts takes the level to the full line on my dip stick. I use
one quart of oil in 6000 miles running at that level. If it ever gets to the add 1 quart, I know it is time to change oil and not just add a quart.

As far as I can tell my dipstick is original. I'm thinking that there are some replacement dipstick tubes out there that are a different length.
Mine is painted blue like the rest of the engine and as far as I know has never been replaced.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana