New engines are a different animal than 40 year old cast iron monsters
designed in the 50's or 40's for use into the 60's or 70's. Dino oils were
all that was available, and your choice was detergent or non detergent, and
multiviscosity wasn't even a word back then. There was 20 wt. or 30 wt, and
10 wt for extreme cold weather. Engines lasted 80,000 to 100,000 miles.
Tuneups every 10,000 miles for engines equipped with points type
distributors.
Now? Overhead cams with roller cam followers, fuel injection, very tight
operating clearances, different metallurgy, synthetic oils, the game has
changed so much, it has all turned into guess work. Even the poorest oils
today are superior to the best oils of yesteryear. Use you favorite brand
in the correct viscosity for your area of the country and you should be
fine. Even the best oil won't make you any richer, or better looking or
more popular amongst the crowd you run with. Change it often enough to keep
contaminates from collecting in your pan, and the filter along with it.
That's what I think, your opinion WILL vary.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
> Go back a week or two and look for a post by Fred Hudspeth on this topic.
> He included a link to a blog that is chock full of tedious language, but
> that describes actual friction protection at failure (of the oil). Based on
> that, viscosity didn't have any real effect on the friction pressure the
> oil would withstand, but oil is the primary coolant and needs to circulate.
> Also, thinner oil drains back faster.
>
> On my old engine, I used Mobil One High Mileage 15W50, and it made the
> pressure gauge happy. But was it the best for the engine? The best oils in
> that test were the latest 5W30 and 10W30's, and though they all overlapped
> considerably, the best synthetics were better than the best dino oils. I'll
> be switching to Mobil One 10W30 with my new engine starting with the next
> change
>
> Rick "recalling Dick P. saying that NSCAR runs at 8000 RPM all day at 30
> psi, but oil pressure is NOT a problem with my new engine" Denney
>
>
> > I have always used 20/50 oil in my GMC. Cold the old pressure reads just
> > under 50 psi. Warm it reads a little over 35 on hot days. If the out
> side
> > temperature is not hot the oil pressure gets close to 40 psi. I have
> been
> > afraid to go to lower viscosity oil. Today I had to go to three stores
> to
> > find 20/50 oil. I was thinking of going to synthetic oil 15/40 in the
> > future.
> >
> > I add Liquid Moly to the oil. I have used the Moly since the late 50’s.
> >
> > Art
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> --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
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