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
