The pump drive either works or it doesn't. If it doesn't, you find out about it in a hurry and drag the car home because the engine is locked up.

My '93 Sub has 244,000 miles. When I start it up cold, the oil pressure will be about 35 psi at idle. When it warms up thoroughly, the oil pressure is around 10 psi at idle. get just a little off idle and the pressure comes up to 20, and it stabilizes at around 50 at cruise. I think what you have been describing is an engine set up with a little extra clearance in the bearings. The oil pump delivery is almost exactly proportional to rpm. At idle the pump can pump its entire output through the bearings while developing a pressure of whatever you said, 10 psi or something like that. As the engine speeds up, the oil volume delivered also increases and now you have "normal" oil pressure.

If you want to tear down the engine do it. Or, drive the car. It has gone 10K miles already and not locked up, so it must be doing something right.

You could also add a couple of bottles of special super-thick oil goop like Wynn's Motor Honey to get the viscosity up.

R.

A high-volume pump may be the answer if you can get the pan off without yanking the engine. If you do this put in a new high-quality oil pump drive.