In general, oils whose weights are on the thin side, 10W-30, 10W-20 and 5W-30 are energy conserving and should not be used in wet-clutch types of bikes. Oil’s whose weights are 10W-40, 15W-40, 15W-50, and 20W-50 are not energy-conserving and are OK for use in all motorcycles.
Because newer...