I know the manual states that I should use 10W40,but I came across some synthetic Shell 10W30 and would like to be able to us it. Has anyone else used different weights and types of oil? I usually us Spectro gold 10W40 at $9.95 each but the $45 could go for other expenses in life. I would like to save some money but not at the expense of my bike. I'm sure there are some opinions about this out there, I would love to hear them and hopefully learn something.