[Oldsmaniac]

I dont think a front oil galley pug is missing either because you would not have 55psi when the engine is started. Are you sure your gauge is accurate?..55 psi at startup and when cold is kinda high for a stock oil pump. Maybe you need to try a straight 30 weight oil. The 4 to 5 psi at idle would scare me but with an idiot light on the dash, thats just about enough to keep it off. If a machine shop built the engine I would ask them Why?...Make sure your gauge and line and engine port is free of gunk so it can read accurate. If all else fails swap the oil pump or shim it for more pressure. I wouldnt let the engine idle long with that low oil pressure.