NC--

It does sound like a leak somewhere is letting the hot, thin oil drain back down into the pan so that any empty galleries must be pumped full before pressure is registered.

But, seems like your cold morning starts should have this problem too, if you shut it down hot.

To answer your question, my truck does not do this but it is a n/a version with a turbo added.

I just happened to have an oil filter base and regulator valve on my bench so took a photo.




If the regulator valve is leaking, then air from the drain to the crankcase can enter the pump discharge gallery and this would let the oil drain back to the pan.

Since the oil filter base is sealed only around the outside with an o-ring, I think a leak could occur between compartments inside the base. This could do the same as a leaking regulator valve. I can't figure why there is no gasket here. For the base to be reasonably leakproof it must be very flat and without any divets.

Also, you should make certain that you are using the correct oil filter with a check valve in the inlet. Almost all do but the lack of a check valve will let the oil drain back too.

My oil pressure when cold also pretty much pegs the guage and then declines to about 55 psi when hot and running at road speeds. Idle is about 30 psi when hot. The manual says that the regulating valve (in photo) is supposed to limit the pressure to 85 psi. My guage reads up to 110 psi max.

Paul