I've always had 993's and just graduated model wise and bought a used 2006 C4S (still have my beloved 993)

I'm not sure if this is a stupid question but my only reference until now have been my 993's

In my 06 C4S, when I start the car everything seems normal, oil pressure sits at 5, and as the car warm up, the highest hits about 4, 4.5. The strange thing is when revs are increased (during acceleration or downshifting) the pressure goes does. For example if my pressure is at 4.5, when i gear down and /or accelerate, it will go to 3.5, 4.

Is this normal? The dealer told me it was ok. I'm just used to my 993, where more gas = more pressure

Car just had an oil change, and i'm only putting 94 octane in it

Only mod to the car is a tubi exhaust

Thanks in advance for any help

Jay

 

Interesting question. I'd like to know as well, always wondered....

 

oil pumps are almost always driven by the crankshaft, and as given that the oil lines and block passageways are a fixed size, as revs increase, oil pressure does as well. Bad engine bearings give the symptom of falling oil pressure as revs increase, but I don't see this as your problem.

I'd wager you have a bad sending unit for your oil pressure gauge.

 

forgot to mention that there is no lack of power when accelerating, and the oil pressure needle is pretty stable, either cruising, or idling

One of my friends had a needle that kept bouncing up and down, but he would feel the drop in power when the needle dropped. It turned out to be the air/oil seperator (he had a 2002 911 C4)

 

BTW, if you're really putting in 94 octane you're wasting your money. It was optimized for 93. Any higher and it's wasted.

 

My choices for octane here are 87,89, 91 and 94, so it's between 91 & 94