Welcome to FABO. I'm not sure what you mean by "losing oil pressure". It's progressively getting worse at all rpms? Just bad at idle? Both hot and cold? The oil pan question makes no sense to me. Maybe you mean oil pump or sump screen? Basically if you know for sure that the oil pressure is not good, it's usually worn out bearings. Sometimes a faulty pump can also cause that but since it's the first thing that gets oil, it rarely goes bad where the bearings are still good. Test the engine with a good live-line oil pressure gauge to verify the oil pressure's actually low. Many times the sender can go bad and give a false reading.
