Oil Pressure drop!

[jimbbski]

While trying to figure out why the car doesn't run "right" I keep seeing an oil pressure drop at the car warms up. At start up cold the pressure will rise to almost 80 psi and then hold at 70 psi for a bit. As the engine warms the pressure will drop down to around 40 psi at 1200 rpm. As the engine reaches normal opp. temp. say 180-190 on the guage the idle speed will drop below 1200 rpm and the oil pressure will drop down to 20 psi. It will even drop down as low as 10 psi if the revs drop below 800 rpm.

I am using Moble1 15W40 oil. I should say that the oil pressure will jump up as soon as I raise the engine speed to say 1500 and it will go as high as 60 psi as engine speed climbs to racing speeds.

I just have never seen this happen with any other engine that I have worked on that was in good mechanical condition. I know this one is as I have pulled the pan just a while ago with no metal in the bottom and cut a filter apart and found no metal there as well.

I guess I'm just wondering if this can be considered "normal" or with in the normal range for VW engines?

[Matt93SE]

no experience with VWs but that's completely normal with the Nissans and Mazdas I've driven. the pressure it a touch low with that heavy of an oil, but nissan spec's something like >12psi at idle and >35psi at 3000rpm at operating temps.

when I first started my engine after a rebuild, I was seeing 75psi at idle, 100+psi (gauge pegged) at 3000rpm. After it got warm, it dropped to about 20psi at idle and 60-70 at 3000rpm.

That was all with 5W30 oil..

But yeah, a multigrade oil like 15w40 will do exactly what you're describing in every car I've driven with a real oil pressure gauge.

[jay05]

My 1.7 does the same exact thing. Been that way since I've been racing it, 7 years. I just make sure to keep the revs up on my way back the paddock after a session.

[chuck baader]

Mine does same with 10 W 30...NOTE: get rid of the Mobil 1 and use a good racing oil...your lifters will thank you!!! Chuck

[pfcs]

Most VW engines (healthy/normal) will show much lower (scary) oil pressures at the cylinder head oil sensor port. The pressure at the sensor port of the oil filter housing is much more comforting to watch. I always used 10-40W Mobil 1 in my A2 1.8 and never changed rod brgs or had a failure.

[jimbbski]

Most VW engines (healthy/normal) will show much lower (scary) oil pressures at the cylinder head oil sensor port. The pressure at the sensor port of the oil filter housing is much more comforting to watch. I always used 10-40W Mobil 1 in my A2 1.8 and never changed rod brgs or had a failure.


FYI: I do use the oil filter housing as the point to tap for oil pressure readings.

[Flyinglizard]

RE oil, I have a cheap effective oil accumulator on my site under "cheaps." photo section.
Just a vertical tube, T'ed into the pressure side. Holds about 1qt. and keeps pressure around 5-6 sec, post shutdown.
MM