Originally Posted by bobs77vet
why so high on the 50 side?
Single weight oil is pretty easy to understand. You want an oil thick enough that when your at max HP, max operating temp, and what ever oil pressure that your bearing surface never touches the crank shaft. Your always running on a very thin oil surface.
Multi weight oil "0W-50" has the cold flow properties of "0 weight oil" and at high temp the properties of 50 weight.
I often have water temps exceeding 220 degrees for long periods of time. I'm happy driving slow when it get down to 190 - 200. This is just a test. This 0w-50 HOT gives me about 40 psi at idle and it climbs to a peak of 75 psi from 5000 - 7000 rpm.
as I said this is just a summer test and if the oil pressure gets to running consistantly to high I will drop back down to something less. My 383 cold had 60 at idle and 80 pegged as you revved it up even with 5W-30. I went with less crank baring width in my 427 build to bleed off some pressure and I don't run a oil restricted top end.