What is oil pressure supposed to be?

[elgyqc]

I have searched and even though this question has been asked before I could not find an answer.
On my newly installed gauge (VDO running off a 996 sender) I get over 80psi on could start, drops to 40psi at cruising speed (2000-3000 rpm) and about 15psi at warm idle.

[gabedrummin]

The oil light comes on at 7 psi.

[elgyqc]

Originally Posted by gabedrummin

The oil light comes on at 7 psi.

Thanks, that is interesting to know.

[blue62]

Old school rule of thumb was add 10psi to idle oil pressure for every 1000 RPM.
Engine oil at operating temp.
That was on 50's-60's engines. probably still "close" today.

[elgyqc]

I found this on the 996 forum.

Originally Posted by Porschetech3

Oil Pressure reading at the head on my 1999 C2 with 130K miles and 5w-50 weight oil.
Cold start = 92psi
Warm idle = 20psi a/c on ---18psi a/c off
Warm engine at 4k rpm = 68psi
These pressures should be typical.

My figures don't look bad, given that I am running 5w-40 weight oil.

[jaykay]

Great question search on here an you should find some pressure data and corresponding conditions.....hopefully it will be non accusump

[elgyqc]

Just back from a couple of hours on the road where I noted these pressures at 180 degrees F
idle 13 psi
2600 rpm - 50 psi
This on an untouched engine (as far as I know) with just under 100,000 miles on it.

[elgyqc]

FYI.
While looking for something else I came across this in the Technical Manual (my conversions to psi).

"5. Warmup engine to operating temperature (80 - 90 C oil temperature).The oil temperature can be read out with the PorscheSystemTester 2 under the "Actual values" menu.
6.The oil pressure should be approx 1.5 bar (21.7 psi) at idle.
7. Have a second person increase the engine speed to 4000 rpm. Read off the oil pressure on the oil pressure tester. The oil pressure should be approx 5.5 bar (80 psi)."

And I found this post in another thread.

Originally Posted by ike84

... Idiot light comes on at .5 +/- .15 bar. Seems pretty low to me (that could be as low as 4psi). But hey, what do I know...

I calculate that as 5 to 9.5 psi

[PLP]

I am not an expert, but from what I read here and there about 996 era engines, location of the oil pressure source is crucial for the correct reading.
Speculation as which one is the most correct...

However, from other cars I used mechanical or sender oil pressure gauge, the values were about 60-90 at cold start (depending on weather - the colder the higher, of course..., so winter, -20 C was 90 psi). Hot, idle, down do 10-15 psi, any speed increase would jump the value right away.At normal driving anywhere (2000-4000 rpm) 20-50 psi.