Re: Straight 40 to thick?
10W-30, 10W-40, 15W40 and so forth. I'm not a chemist but I learned that the multiple viscosity oils are blended for all weather use, and the "W" means winter.
So you get 10 weight on the start up when the oil is cold (or 15 weight) and then it does all that magical chemical heat business as it warms up inside your engine. West coast states and southern states not need to worry about that so much as you folks in Montana, the Dakotas, and Maine, etc.
Foley
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