Oil Change

[carsixten]

Originally Posted by smokey

Did I also mention that I use car oil, always have and always will, usually the Castrol GTX 10w40. Never had a problem with any of the 40+ bikes I have had.

Smokey. I think I agree that using Castrol 10w40 wouldn't harm the motor, but what about the clutch? Everything credible I've read says that any oil marked "energy conserving" with the API grade SM or higher, have friction inhibitors that will make your clutch slip.
Is that true, or just more BS from the marketing department?