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FE Technical Forum / Re: Oil viscosity, 10w30 or 20w50 for 390
« on: January 05, 2012, 09:10:43 PM »
This is just my experience. I have a blueprinted HV pump with a high pressure spring. I had the best oil pressure when I went with 15w50 mobile 1. My idle pressure when hot was 10 psi, but when I switched to the 15w50 it picked up to 20 psi in the hot summer months and 25 psi in the winter. With the high pressure spring pressure was never a problem except at idle. Unfortunately I can't remember the clearances as I built it in 1998. I really like the 15w50 mobile 1.