Don't understand the negative comments re briggs engines and throwaway life. According to Rick Zeckmeister, Briggs vice president of marketing and planning, the four-stroke mower engine is designed to last the life of the equipment it's used on, which could be about 12 years, without an oil change. Briggs says the engine will set a precedent in the lawn and garden equipment industry, and none of its competitors has an engine that doesn't require an oil change. The new engines are better built with better cooling and lower temperatures so oil quality is maintained. In any case, the engine handbook says that oil can still be changed if you want, and is made easier as new oil filler design. I will always change oil every 20 hrs of use anyway. In my own case, as a professional contractor, I always change oil carefully and avoid any contaminants getting into the engine. I have three 17 year old Hayter mowers with Briggs engines that are still running very well and efficiently because I change oil and filters regularly. If you neglect any machinery, don't be surprised if it fails...