What should my oil pressure be at idle? I'm asking because my car started to run hotter than it should and the oil pressure is lurking between 15 - 35 lbs, would this have anything to do with the engine runing hot? ie, is the engine being hot making the oil thin out, or do I have gasoline dilluting the oil?

when driving on the highway the oil pressure seemed low too, a bit above 20 lbs, and recently it seemed like the OP was fluttering, not dropping, i thought it was the gauge playing tricks.

any thoughts?

are u sure u dont have an oil leak ... losing pressure.... and not lubricatin everythin makin it run hot?

i've checked, no leaks...

Probably the gauge, so I'd get another gauge and double-check it. 20 lbs at idle sounds OK, but low for highway speed.

Here's the Nissan specs for the A10 and A12:
idle: 13-17 lb/sq in
regulator: 54-60 lb/sq in

the pressure got better once the engine cooled down some, around exactly 1/2 way on the temp gauge it seemed to get better, I'm gonna watch it tomorrow. Could it be the 89 octane gas?

naw, I only run 89 octane fuel. Even if it was a bad batch of gasoline, it wouldn't cause the oil pressure to drop.

If fuel dilutes the oil, i would think pressure would still be good until the bearings wear and start knocking (bearing knock). At some point, the pump cannot put out enough volume to fill the (worn) clearances and pressure drops.

The other thing to consider is what grade oil are you running, and also has it been changed recently, as if the oil hasn't been changed for a while this can effect oil psi as well.

10w30 i think, and it was changed 1500 mile ago or less.

I'm kinda mystified by the whole thing. I have a feeling it's related to fooling around with the mixture on the carb. I'll have to figure this out.

Also, what is this about water pump cavitation over 120 km/h that I was reading about? because this all started by going really fast on the highway. Is this a problem on the A15's too?

B210sleeper, I don't think the carb mixture can affect oil pressure.