As I said in your other thread, this is the internal pressure relief valve doing its job. If the oil pressure were allowed to spike over 4 bar, that would be in excess of 58 PSI. Bad things can happen to the engine at pressure that high: oil can't travel to the places it needs to go, the oil-pump drive can shear, oil pump drive would have massively increased wear, oil filter housing explode, and other things. Oil is a fluid and is much thicker at ambient temperature than it is warm. Even 0w oils get thicker as temperatures drop. Sorry you tossed money out the window for the sensor but your car is working as designed.

 

I don't mind if I tossed money on the sensor, but I don't think this is normal and I want to get the car fixed. The reason I don't think it's normal is because the car had never done this before, it started all the sudden, and none of my other cars (both of which have oil pressure gauges) do this.

Does your Panamera do this?

To be clear about what's happening...on a cold start, for the first 3-5 minutes the oil pressure bounces around between 2-4 bar at idle. It jumps from 2 to 4 very quickly (looks like a tachometer as you rev the engine), and then slowly drops back down to 2, and then repeat. Once the engine warms up, oil pressure is stable based on the RPM.

So...while I understand why the relief valve is opening at 4-4.5 bar to relieve the pressure and that its doing what its supposed to do, my question is why is the oil pressure getting that high in the first place?

Is this normal for Panameras? Mine is a 2012 Turbo.

Thanks for your help.

 

My 2012's oil pressure gauge does the same thing until it warms up. IMHO, everything you are describing is normal. As I said earlier, the pressure is getting that high because the oil is cold. Oil is thicker when cold, and it gets thicker the colder it gets. It's physics. Older oil with some miles on it will eventually shear down to a thinner viscosity, even when cold. Its why used oil generally has a lower cold pressure than new oil. Nobody is stopping you from loading up the parts cannon and firing away at the car, but from my perspective - this is normal and nothing to worry about until the car starts to tell you otherwise via a code. Now, if the oil pressure gauge is rocketing back and forth like it was being switched on and off, that is not normal, but that doesn't sound like what you are describing.

Edit: As to why most other cars do not do this, its because the gauges on the dash are purposely dumbed down to hide fluctuations like this. The reason for this is to keep owners from dragging their cars into the dealers for what is a normal reading. More often than not, the gauge on the dash is showing data that the ECU wants it to show instead of an actual straight-from-the-sender reading, and anything within a range will be interpreted on the gauge in the exact same manner. As an example, anything from 2-4 BAR at an oil-temp of below 150 degrees (and I am pulling that temp out of my butt) would be interpreted as "straight up" in other vehicles. Once the temperature threshold crosses a set degree, then the gauge may (or may not) switch over to more of a non-filtered reading. In my 95 Chevy, the dash oil pressure gauge is a filtered-gauge and the sending unit itself does the filtering. Swapping out the oil pressure sender for the police-package sending unit is a very common mod to increase accuracy.

 

Here's a video I just recorded this morning. My gauge is all over the place starting @ :40. When the car comes off of high idle @ 1:06, it comes down a bit, but tapping the gas (1:22) shows it bouncing way up, then down, then up again then normalizing. It's fluid-dynamics at work and TBH, I really don't feel like typing out the entire explanation. Cliffs notes: Pressure goes high from thick oil and RPMs, bypass opens, pressure goes down concurrent to RPM's going down, valve closes, pressure spikes (equivalent of 'water hammer') because the bypass closed, valve opens, pressure goes down, stabilizes.

 

Thank you for taking the time to do that, I appreciate it. This is pretty similar...I'd say the range that mine fluctuates is slightly greater (dips a little lower and also climbs a little higher).

But more importantly - I noticed that yours does this mainly after you rev the engine, whereas mine will do it just sitting at idle, without me ever touching the gas pedal or the RPMs ever climbing. Still no cause for concern? I suppose that could also be because I just had an oil change, so oil is brand new. Just want to confirm.

Has yours always done this in cold weather? Have you owned it a long time?

For me, this is my 2nd winter with the car, and I don't remember it ever doing this last year. I think I would have noticed. But - it's also my first German car. My Japanese cars have oil pressure gauges and are always stable on a cold start, but I think they're running 5w-30 rather than the 0w-40 in the Panamera.

 

The car also does it when it is sitting there at cold-idle. My car has always done this and its more pronounced in cold weather. I suspect that Porsche may have made some coding adjustments to later model years to mitigate the gauge movement when cold for this very reason. I'd also guess that the difference between the gauges in your Japanese cars and the Porsche are the dumb-gauges vs real gauges. The Japanese cars are more utilitarian/mass market and the Porsches are generally geared towards enthusiasts. Mr. Hipster Camry driver will probably never lay eyes on the oil pressure gauge, and if he did, he'd probably not even know what he's looking at so the coders at Toyota made is a go/no-go gauge.

If the gauge bounces around like this when it's hot, that's something to look into. It would be a sign of the valve itself being bad, which is integrated into the pump. It is possible that a bad sending unit would do it - but the car is smart enough to throw a code during the initial system tests, and even then - the vast majority of electronic sending units fail outright. They don't die, then come back, then die, then come back. In the case of electronic sending units used for pressure and temp, when they fail the gauge usually flatlines or pegs itself because it shorts internally to ground.

 

Gotcha. Thanks for your help, very much appreciated.