Sorry, didn't have time to read all the replies, so this may have been said already.....
I would not run anything in an integrated engine/transmission that is not Morotcycle Specific API SG/JASO MA. The SG guarantees that there is lots of zinc, etc., and the MX guarantees that it is ok for your wet clutch.
Car oils just aren't beefed up with the extra high pressure additives, intended for use in a transmission. Not sure why everybody insists on using them in their bikes??? Guess it's because you can get them cheap at Wally World.
Nice informative article, from MA Action:
http://www.thumperfaq.com/oil.htm