WOW! man there is some real oil pressure talk going on here. I don't know much about how and why all I know is my 1949 chevy truck with a 1955 235 cid engine had about 15# of oil pressure on start up and after it warms up it will fall to one needle width past '0' that zero, goose egg, nada, nix, nothing. I will try certain thing that I've gotten from 'Stovebolt' who knows. I would like to see some pressure when warm and at idle. No knocks bangs rattles or anything like that so MAYBE I have enough pressure. Who knows. Thanks for sharing many years of knowledge with me. It's a good thing.