My 3.5hp Briggs and Stratton lawn mower engine is on its 32nd year of running 10w30 dino. It has lead a tough life, mowing model airfields plus many properties besides my own. Compression is down but still good enough to start and run full out, I use it strictly on the airfield now, 3 to 4 hours straight running every 2nd week, only stopping to fill the tank when required.