i used to run it in every tank of a Chebby 230 I had. Only thing it really did was stop a ping. Use it in the gas tank and crankcase and you'll quiet down a noisy motor darn good. What are you trying to accomplish with it? Seafoam?
Do you mean Marvel Mystery Oil ? When leaded gas disappeared, and I was still riding my Triumph, I'd put a shot in when filling up. My exhaust valves would still be pitted by the end of the season. Don't think it can hurt anything, but don't think it really does much. The can sure looks cool though