Thanks to all for the suggestions. I pulled the oil cooler and the
oil pressure valves this weekend and all looks good. The Oil cooler
tubes are almost scary clean. I did change the oil, but the only oil
I can get here is a 15w-40 for diesels from BP. Believe it or not,
that or a 20w-50 is all that I can get here. I am getting about 10-15
psi at idle and about 50 psi at max speed. My manual says that I have
seperate senders for the warning light and the gauge. The time the
pressure really dropped off and the light came on was right after
pushing the engine hard for a while (on plane). After I change the
oil and checked the cooler and such, I cruised around for an hour or
so and the pressure never went below 15 psi.