Time for the first oil change. Book says 20-40. Whats everyone else using? I use 10-40 Amsoil Synthetic in all my other bikes and purolator filters. Looking for a little feedback. When does one make the switch to synthetic? I have always done it on the first change. No problems with any bike yet. I know these ?'s are kind of frowned upon on other bike forums but its good to know whats working for riders and whats not.