That is a very good post .... Thanks Phred.

So how do you know what viscosity to use on an engine ie.. 10-30 vs 20-50?

Does a new engine require thinner oil because of the closer tolerances in the bearings? And at what point would you have to go to a thicker oil (0.001-0.002 or more)?

I know I've opened a can of worms here but lets just assume that were talking about moderate operating temps.

Ed! Start a new thread. A discussion that good will just get totally lost here...

steve77