I've noticed when the engine is idling at around 750 rpm the oil pressure shows to be 30psi when I rev the motor to 1500rpm and beyond it comes to 60psi. Is it normal to be at 30psi at Idle? In my 1988 non turbo I'm using 20W-50 and its fairly new.

 

That's excellent! However, the stock gauge especially being this old is notoriously inaccurate. A mechanical gauge would verify your real pressure readings. But like I said, those numbers are superb.

 

What is the oil pressure spec? I know the first gen FSMs list it at idle and 3k rpm, but I couldn't find it in the S5 FSM.

I've got a stock '90 turboII

 

Engine warm 64-78 psi @ 3,000.

 

I agree with using a mechanical test gauge to verify readings but quibble a bit with the first part.
The gauge is probably fine, it's the sending unit that will wear out and require replacement.
The stock oil pressure gauge (including the damping capacitor) accurately tracks with aftermarket gauges I've run concurrently. It does not react as quickly (which I find preferable in a street car) but has been very consistent with the other- supposedly superior- aftermarket units.

Unless you have a compelling reason for ditching the whole cluster, I'd keep the stock gauge and get a new sending unit.

 

Doh, I barely break 45psi on the stock gauge. I guess I need to verify if it is still accurate, or in need of replacement

Thanks

 

Correct me if I'm wrong but aside of having a leaky oil system a low oil pressure could also be caused by excessive diluted oil (oil & gas).

 

I should reitterate, "stock system". Personally, I do not know what is the failure point (gauge/sender), but I know overall everyone says "stock is inaccurate".

 

thanks for this info