The car runs flawlessly. The oil pressure goes up to 80 PSI when cold but drops off to about 12 when hot at idle with the specified 5W-30 oil. The in dash gage was verified with a high quality mechanical gage.
I am thinking about using synthetic 0W-40 oil to increase the oil pressure at idle.
Is this going to cause any problems?
The 80 PSI seems a little high. What should the pressure relief valve be at?
Thanks, Scott
I would just use the oil recommended for your car. I don't see how 12 psi at idle is a problem. But what does the tech manual for that engine say.
10psi per 1k rpm is a good rule of thumb as far as rules of thumb go.
Steve B.
Good question. I looked that up. The one section does state that the low pressure indicator is to show at 4 PSI. The engine specification section states 15 PSI minimum at 900 RPM. I don't know what the actual idle speed is but it is close to 900. I'll check it when I drive to work today.
It idles at 800 RPM. So at 900 it is right at 15 PSI. I'll switch to the
0w-40 and see what happens. I'll report the results.
Had a similar situations with a 4.3 S-10 Blazer at ~180K miles. idle oil pressure poor with 5-30, but fine with 20-50 or 15-40
I'd go with 15W-40 oil for diesel engines (Delvac, etc) you have 150K on it, lots of wear and lots of slop. Oil intended for diesels has a load of anti-wear additives in it....at this point you're trying to get max life out of the motor before rebuild, not max economy, right?
likely, your rings have some wear and your oil is being diluted (with gasoline) over time, too.
Plus, 15W40 comes in gallon or 3.8l bottles and is reasonably priced vs 20W50 which is becoming a specialty item in some areas, anyway
Be sure you have GOOD PCV function, this will help to reduce the dilution effect.
My opinion...flames welcomed and ignored...
--Don Don Byrer KJ5KB Radar Tech & Smilin' Commercial Pilot Guy Glider & CFI wannabe kj5kb-at-hotmail.com
"I have slipped the surly bonds of earth; now if I can just land without bending the gear..." "Watch out for those doves..."
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