Mobile 1 SYNTHETIC is the factory fill in GenII engines. We live in midwest, and use 10w-30 and it works well...see VERY little oil consumption in our Vipers...used for highway driving only, no racing. There are a million "recipies" out there...pick your oil usage to suit your driving conditions. Best price on Mobile 1 Syn is somewhere like Wal-Mart...watch for sales, and watch for the 5 quart jugs as well. Suggest Mobile 1 filter as well...M1-204 .