I have a 1991 Comanche Pioneer, 117000 miles, great shape, was show truck for many years with previous owner. Coming back from long highway trip, oil light would come on at idle. I had done oil change about 300 miles before so oil was good. Short trips no problem but more than 20 minutes and light on at idle. Changed sending unit and it stopped. About a week later after 50 mile highway run light on again at idle. (The light flickers on, never constant). I changed it over to pressure gauge. Stay around 30lbs maybe up to 35 on highway, but after warm it droops to 10-15.
No heat issue, never knocks, engine sounds fine, not burning oil. I changed oil from 10w30 to 15w40 but no difference in pressure. Oil filter is located on left side of motor, up high and sending unit is attached just below. I think this may be aftermarket mod, there are others.
Could the oil reading be off because of location? The engine seems to be running fine with no noise is 10-15 ok?
Attached a couple pictures of oil filter location and one of truck.