I have a self-propelled Craftsman 6.75 HP mower. I bought it new in '01 or '02 here in MI. It has an "Eager 1" engine, is that made by Briggs and Stratton? Is it good or on the cheap side? It runs great and starts on the first pull, even after winter storage. How many mower hours is the equal of 3,000 miles in a car? I'm currently using SuperTech 30W every 12 hrs but am thinking of switching this spring. What would be the better oil for it: 30W Rotella or 15W40 Rotella?