I like these oil threads! I've just reread my manuals. The Briggs manual says my engine will like SAE 30 which matches up with everything I grew old with. My current oil is B&S SAE 30. The Bad Boy manual sez 10W30. And in very small print: "BB Synthetic Blend ... recommended." I live in hot country. Both my mowers get SAE 30 and my 11 HP Universal diesel on the boat: Rotella SAE 30. Now that my car has over 100k ... I'm going from 10W-30 to straight 30 next change. I took that little side road, and the modern world passed me right by.