Kohler recommends using a high quality detergent oil of API service class SG, SH, SJ or higher. You can use any make or type of oil you want as long as it meets those recommendations. I use Mobil 5000 10w30 in all my engines, Kohler, Kawasaki and Honda, have ever since I can remember and never have had a problem. The key is to change your oil and oil filter regularly. If your in Hawaii I'd use the 10w30. Another thing, if this is a new engine stay away from the Synthetic oils for at least 50 hours until the piston rings properly seat.