Fluctuating oil pressure

[Spaceman]

Yeah same here. I haven't started my engine yet but I've cranked it with the spark plugs out, and at 250 rpm the oil pressure made it up to like 60 psi... The oil was sort of cold (high 50's F), but that still strikes me as pretty high so I think I should make sure neither of those plungers is stuck.

[pappas]

I have always found the initial, start-up, oil pressure in my turbo will be between 70 psi and 90 psi. On cold days it is nearer 90, warmer days nearer to 70 deg f.

However, after the oil reaches 100 deg f on taxi, PSI drops into the low 50's. After a few minutes of flight, PSI normally runs in the 30's to low 40's. Kerry has written to tell me that they use 10 psi per 1000 rpm as the rule. More psi per 1000 rpm is good, less is not as good. But he said that oil pressures in the green are, after all, in the green.

The initial temperature of the oil makes a big difference. As long as OP is not over 100 psi at startup, you are good. As long as you don't take off until the oil is over 80 deg f,(preferably at 100 deg f), the OP will likely be lower than at start-up. After a climb-out and short cruise, and the oil reaching normal flight temps, the pressure should be down where it needs to be. All normal, not to worry.

[Hasbenij]

Gents,
Could I jump in here and ask another question?
I am getting approx 25psi/idle when the oil is cold and 60psi plus during run up. This is a 2180 aeroconversion. After doing a couple of high speed taxi's, the pressure drops to as low as 12psi at idle. OT is approx 170-180 deg.
I'm using Castrol 20-50w and putting around 3qts in being I am using an oil cooler located on top of the engine.
1. Does anyone know how much the oil coolers normally lower the level from the crankcase when in use?
2. Has anyone used a straight 40w oil?
I will be checking the oil pressure sender with a manual gauge to verify proper operation.
Any suggestions?

[Area 51%]

1. Does anyone know how much the oil coolers normally lower the level from the crankcase when in use?

The top mounted cooler has a capacity of 8 oz. For those of you that have the steering wheel on the right-hand side of the dash...it's between 250 and 260 ml.

I wouldn't add extra oil to account for that volume though. I'm sure VW figured that in when they marked the dip-stick.