Macster

The oil pressure gauge (sensor) fitted to the engine may not be that precise/accurate of a sensor. There can be some dampening of the pressure displayed, almost certainly there is, as I recall when I had a direct reading (a small diameter nylon tube ran between the engine block oil pressure port and the gauge) oil pressure gauge in one of my cars, my first car a Datsun 510, the oil pressure needle twitched like crazy.

It is not easy to fit a high quality gauge to the car so one can monitor oil pressure while driving.

In the shop the tech could fit a test gauge -- probably 'T' off where the factory sensor is located -- and with the engine warmed up observe hot idle oil pressure and then bring RPMs up to say 5K and note oil pressure at this engine speed.

The factory manual probably has a call out on oil pressure but I don't what off hand this is. (For my 996 Turbo it is "Oil pressure at n=5000 rpm, T = 90C: Approx. 6.5 bar".) (I seem to recall -- but don't quote me -- the factory manual for the 996 NA engine has a slightly lower oil pressure under similar conditions specified.)

In some way you could then "calibrate" (at least in your head) the car's oil pressure reading with the test gauge.

(I did this with the coolant gauge of both my cars. I observed the OBD2 coolant temperature vs. needle position over time and thought I had it all worked out. But after a while I just said to heck with it. I don't need to know the exact coolant temperature only that the engine is cold, warm/hot, or too hot and the temperature gauge is plenty good enough for that.)

Based on what you posted the numbers are in the ballpark.

BTW, my Turbo's oil gauge needle bounces around a bit sometimes when the engine is up to temperature and idling. Been doing this for as long as I can remember ever since I bought the used in 2009. There is probably a marginal connection or the sender or sensor is flaky (?) but the sender is hard to get to and I haven't bothered to replace this. If it were easier to get to I might try a disconnect then a connect to see if this improves the sensor's behavior. (Surface corrosion can develop that can interfere with the voltage signal sent to the DME and if this is the case a disconnect/reconnect can be the cure.)

0911

My gauge is pretty stable, more so that your one and others I have driven are also stable. It sounds like you may have intermittent oil flow (partial blockage) or a faulty gauge.

RossKatz

I just replaced the oil sender unit on my 2002 911 4S a few months ago and the oil pressure seems a bit erratic.

My 996 used to start at 4.5 bars, then consistently go down to 3.5 when warm and stay there.
Now it starts at 5, eventually starts going down to 3.5 when warm, then goes down between 1 and 2 when in neutral.
When I step on the pedal, it goes back up to 4.5 - 5.

Is that normal?
If not, any ideas (e.g. replace Sender Unit again in case new one is faulty)?

moosetaco

That sounds about normal to me based on what my 996.2 does.

Pegged about 4.5ish til warm then hovers around 3 for awhile, then finally 1.5ish when idling.

Once the cars fully warmed up pressure rises with throttle input. Mine had a new sender installed about 2 years ago because I never quite hit 5. Still doesn’t quite reach 5.

🤷‍♂️

Porschetech3

Yes, it is working normal now (was not before)..

Mike Murphy

Agree

dan_189

+996 on working correctly

The biggest change I noticed with the new one is stability. The old sender would read correctly but it moved erratically - the new one is more stable