My Briggs 22" push mower hasn't had an oil change since I've owned it in 7 years, mind you I do only need to cut my grass 8-10x a year, mostly weeds! :thumbsup:
Apparently Briggs and Stratton has been developing an engine that will no longer require oil changes. They say it should last the expected lifespan of the typical walk behind lawn mower, which is about 12 years. These new engines will be available on Walk Behind Lawn Mowers in early Spring of 2015. New 2015 Briggs & Stratton Engine | Top Rated Zero Turn Mower Reviews