Adding Marvel Mystery Oil (MMO) or something like Lucas Upper Cyliner Lubricant has been mentioned here (lawnmower forum) before in a positive manner. Supposedly... they can lubricate rings for longer cylinder life and also clean and lubricate valve seats. This may mean longer cylinder life and help prevent burned pistons as they provide upper cylinder lubrication. Also..reduce carbon deposits. (Oil may have a hard time getting to the upper cylinder?) The Lucas product says you can use it continuously in any engine. Recommended treatment dose is about 1 ounce/4 gallons. Any one have comments or better yet experience with these type of products?