Oil Pressure Issue

Intermittently losing oil pressure. Guage drops and yes, valves click if I continue to run vehicle.

Trustworthy mechanic (really), can’t isolate problem. Wants me to allow another mechanic to investigate.

Have the oil pressure sending unit removed and substitute an oil pressure test guage. If the oil pressure starts out good, but drops the longer the engine runs, the lower end of the engine, rod/crank bearings are worn out.

Tester

What kind of vehicle is it? Some have specific engine issues that can cause this sort of situation. When does it exhibit this symptom, only when good and warmed up, or when cool and just started up?

While you can’t do much in the way of diagnosis by yourself, check the specifications in your owner’s manual. There is a slight chance that your oil may be too thin. You also left out all the vital information such as yearmakemodelmileageengine.