I have a 351W motor that is stroked to 418. Forged rotating assembly with a billet roller cam. It has .0025 to .003 main bearing clearances and .0024-.0027 rod bearing clearances. These clearances are a bit larger since it is a street / strip race prepped motor. The motor has a Mellings HV oil pump. The engine consumes little to no oil. Its in a classic car that only gets 500-1500 miles/yr. Oil changes 1 time per year when going to sleep for the rainy season. I have always (8years) used Royal Purple (10w40, weight I think) with a Wiks filter. With RP my warm idle pressure was always around 18-22psi and would ramp progressively to 50psi when off idle. I recently changed to Mobile 1 (5w30) because it was on a huge sale at costco. Now my oil pressure is at 12psi at idle (850 rpm) It ramps up the same as before to 50psi. I use a Autometer electric oil pressure gauge, but see no reason to believe it isn't accurate. My questions to you Oil Experts is: 1) is 12psi idle pressure enough with full synthetic oil? 2) what weight oil should I use? (5W40 comes to mind). What brand of full synthectic do you recommend? (Castol Edge, M1, RP come to mind). Your reasons why would be great to understand. I enjoy reading this forum. Regards, Alan
Last edited: