ANY oil pressure at idle hot is fine. Our 500" inline 6 cyl CNG buses barely register @ idle hot and have NO issues, dragging around 33K pound transits running 21psi boost. The big diesels are the same lot's of boost and hardly any hot idle oil pressure- 10 psi/1000 rpm just works, more than that you are throwing away power and overheating your oil by pumping it past the bypass back into the crankcase.