At an idle in my 91 z28 L98 100K miles how low should the oil presssure be? I run 10-30 castrol and at an idle after it warms up it goes to the line between 0 and 30 on my stock gauge. I have a new GM oil sender so i know its not the prob. when i go the pressure goes to like the line between 30 and 60, It just seems too low for me im afraid my motor might need a rebuild.

 

mines the same. Think its one of those things were they just didn't plan it to good when building the car.

 

BBZ,

A good rule of thumb is 1 pound of oil pressure for every 100 engine RPMs. 1000 RPM = 10 PSIG.

Newer engines have the oil pumps sized to run really low pressure at idle RPMs, just to save the energy (and fuel) required to pump the oil. It's another way to improve overall fuel mileage and improve corporate fuel economy averages - and it drives me NUTS! I personally like a little more oil pressure than that.

 

Vader's rule is good for estimating survival. Normally these cars do about 20-25 at idle and 50 or so cruising, so it sounds like you're well within the normal range.

100k miles is like brand new as far as that goes. If the engine has been well taken care of that's fairly low milesage. Just for comparison's sake, I have a motor in a 78 El Camino that has 343k miles on it, and it's never been apart.