The water-thin oils like 5W-20 don't cushion moving parts as well as thicker ones, so it would be hard to give me a truckload of that stuff to run in a stovebolt engine. It makes them sound like there's a bunch of little guys with sledgehammers inside, trying to get out. I run 15W-40 in everything on the farm, from lawn mowers to Diesel tractors, and all the cars and trucks. Buying it in bulk in 5 gallon buckets helps, cost-wise, as well.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!