Anything will work!!! Target 55-60 psig at 6Krpm's. at 80C. Once again anything will work. I have found with each set up in viscosity you gain about 5-7psig. so if you went from 10W40 to 20W50 i went from 57 psig to 63 psig. 10W30 to 10W40 was 55 psig to 60 psig. Once again any will work. I had an engine that went from 52 psig to 42 psig at 6Krpm and the engine was immaculate. to make a long painful story short in the end the culprit was a
oil pump with loose tolerances. I tried 20W50 and the
oil pressure went from 57 to 52. when i replaced the
oil pump the 20W50 was 67 psig!!! at 80c and pegging the gauge at 75 psig when cold. I changed to 10w40 and it is now 55 at 3Krpm and goes to 61 psig at 6krpm. as far as idle without a specific rpm given its meaningless. 200 rpm will gain 10 psig oil at idle, anything above 30 would be more than adequate even 25 at idle forces are low low low.