My brother has a 2001 Z28 A4 98K, regular old oil

I have a 2001 Corvette C5 Coupe A4, 130K, Mobil 1 10w-30

At start up they both have around 40 psi, than his Z rises to 50 while driving, and approaching 80 under WOT, never gets below 45 at idle

Mine as soon as it gets warm goes down to about 28-30 psi, 35 while driving, and 50 WOT... however today I did change the oil because I didnt know what to do, as it was idling at 22 PSI at red lights

What gives? Is my LS1 about to take a **** on me?

Same motor, same year

We went out and ran them both, mine came out on top all across the board, but this is really freaking me out

Any thoughts?

 

Are you going by the stock gauges? Then thats the reason why there different. Stock gauges suck and just give you a general idea of if everything is running good. Im sure if you hooked up a autometer or some kind of accurate gauge that they would read the same.

 

2002 service manual for f-bodys says the 5.7 needs 6 psi at 1000 rpm (sort of idle)

 

I think you're alright. My T/A's oil pressure is exactly as what you're describing. I got no problems. *knock on wood*

 

its just a little looser from the mileage.and the stock gauges are off on some cars.

 

........and they come with different tolerances from the factory. My uncle is a Cadillac, Buick, GMC dealer and my 200K+ LM7 in my Z71 has better OP than some of his new trucks. My truck idles 45psi hot and runs 55 at hiway speeds. My old 90K (at the time) LS1 had better OP than his CTS-V the day we traded cars. You are fine........

 

I had relatively the same thing with my Z when I first got it, very low psi@full warmth.

It HAD mobil 0w40 and a FRAM filter(prev owner) in it.
Switched to an AC Delco filter(normal size/spec) and Castrol 0w30, psi rose 10 psi across the board and NEVER got that low again with that combo. If you have a FRAM filter on, throw it in the trash!!

Most gauges should NOT be taken as gospel, but are a relatively good indicator

 

mobil 1 is some of the problem,my car has low oil pressure with mobil 1.i run 10/30 valvoline conventional.

 

this is what GM SI says for oil psi specs for an 01 vette at operating temp.

6 psig at 1,000 engine RPM
18 psig at 2,000 engine RPM
24 psig at 4,000 engine RPM

I'd say you have nothing to worry about, and like some of the other guys said, stock guages aren't always exact.

 

ditto on the fram, my old 98 ws6, always was 40 at idle, I changed the oil at my apartment complex and bought a PF-44 filter, but somebody switched a PF-47 inside the box, so I had to get whatever filter I could find (car on jackstands with the oil out of it)

Fram was what they had, I replaced it less than 100 miles later after the pressure was around 28, put the delco back on and startup (hot engine) back at the normal 40

Ryan

 

also, the f-car and corvette have different pressure senders, one to the dummy gauges and one to the pcm (corvette)

Ryan