IMO ...... of all the oils out there for auto, bike's, four wheelers whatever you may have, I wouldn't run Mobil 1 in my lawn mower. I've done personal tests of 90% of oils out from full syn's to plain generic conventionals, and in the vehicles I used as test platforms Mobil 1 was near the bottom. For example, i ran a series of test over a 20K span on a mild 355 in my 86 Monte, changing the oil every 1k allowing for work in time and whatever, and in that 1k of test time, that 355 "ATE" 1.5 qts of mobil 1, but yet only showed low .25 qts. of a conventional castrol gtx. plus I always used the same grade viscosity. I have a friend who had a 1992 Pontiac TranSport with a 3800, and; althought it's hard to be 100% due to 3 instrument clusters, we ball-parked 730K, yes 730,000 miles on the original engine and transmission with no major work. Engine oil .... Castrol GTX 5w-30