[OrrieG]

I have never had a six or sbc with stock or near stock oiling systems that you could not use the oil pressure gauge for a tach!. Good news is they have good systems and I have ran them with the oil at 15# or even a little less at idle for years without a problem. Usually it picks right up to 30+ off idle, if not then you have a problem. If the level is good on the dip stick I would not add more, too much and it gets thrashed by the crank which can add air bubbles or foam it and could cause problems.