If you MUST pour abrasives down a carburetor, don't use anything but Bon Ami. Mix a couple of teaspoons with a lightweight oil like Marvel Mystery Oil, and pour it through the carb at a fast idle. Follow it up with large quantities of oil to try to wash the rest of the abrasive out. Then go buy a new set of piston rings, and do the job right.
The DELO oil will work just fine in your stovebolt. I've used it for a lot of years in gasoline engines, but don't expect it to reduce oil consumption any. 15W40 is slightly THINNER than 20W50, staying at the thickness of 15W oil all the time, but lubricating like 40 weight when it's hot.
Jerry
