Oil pressure

pontiac
bonneville

#1

After an oil/filter change, I am experiencing a REDUCTION in oil pressure during highway driving while accelerating. I’ve changed oil/filter AGAIN, using a combo of 20-50 & 10-30 (owners manual calls for 10-30 in the summer). Plus i’ve added Lucas Oil.

These things REDUCED but not eliminated the pressure losses reflected on the gauge.

The oil filters have been Purolators Pure 1.

I’ve used various name brand filters over the years & have used various oil additives (rislone, mystery oil), as well.

129,000, miles…2000 Bonneville…regular 3800 engine.


#2

Why are you mixing 20w-50 with your 10w-30? Additives are worthless in most circumstances, and could be contributing to your problem.

Check out http://www.BobIsTheOilGuy.com for information about additives.

I suggest you have a mechanic measure the ACTUAL oil pressure and stop relying on the dashboard gauge. They are notoriously inaccurate.


#3

Have you checked the oil level?

I think you have over fixed on the oil thing. All modern oils today are good and really don’t need additives or special mixes. If you have changed the oil as specified, then I would look elsewhere than the oil or additives.

I agree with MC, check the actual pressure with a different tool.


#4

I also avoid any additives. You really need to get the oil pressure checked with a calibrated oil pressure gauge. The dash gauge is about as accurate as a 99 cent air gauge.


#5

Sounds like an aeration or foaming condition.

When you say “acceleration” …are you referring to what amounts to a (would be) 1/4 mile time trial? The reason I ask is that there can be conditions where, especially in GM’s, the oil can be somewhat cached in the valve covers, running the sump low enough for cavitation to occur.

Your drain back pathway may be restricted.

Does this have a consumption problem? If not, ditch the heavy weights. If you’re so inclined, pull a valve cover or attempt to inspect for heavy deposits through the oil add hole if it’s not baffled. If it is fouled, use your cleaning agent of choice. I prefer Auto-Rx (www.auto-rx.com)