I change my push mowers once a year and they get used pretty used continuously in Florida, because of lack of seasons. The oil always looks like new when it comes out and I sometimes think that is overkill. The generators, with the Briggs motors, I change once a year too, they get synthetic oil, but that oil looks black when I drain it, but they run continously for sometimes 8 hours, when camping.So they get alot more of a workout.