Briggs & Stratton Original Equipment 100005 4 Cycle Oil. (18oz Bottle) Briggs & Stratton Lawn Mower Oil is formulated for 4-cycle air-cooled engines. Don't overfill the crankcase when adding oil. Too much oil can damage the engine.
For optimum performance, you should change the oil in your small engine after the first five hours of use and then annually, or every 50 hours of use (whichever comes first).