I use WalMart house brand 10-40-----has worked for over 500,000 2 wheel miles---from BMW K-75,, Kawasaki Concours, TU250-GS500E Suzuki---2 Miatas, Mitsuibishi Mirage--11 Maxi scooters----never engine trouble and I ride a lot-----motorcycles no clutch slip. I, however believe in frequent oil changes.