[TQ29m]

That's at least a $64 question, I've been running Castrol GTX, 20-50 in my 600 Yamaha, with no issues, and in the previous old Honda, since 1991. I would hate to change at this time, but I've heard that the oil that Yamaha recommends works well also, but it is awfully thin to suit me, and some of the synthetics don't tollerate alcohol too well, some not at all. Now, ya got another couple of thoughts! Look for a lot more. I called Castrol, long ago, and got the scoop from them, after I had called Valvoline, which had been my choice, and I switched, seems Valvoline now has a high dollar racing only oil out, and I know a few that use it, but I wasn't sold on it. Bob