I recently got a '99 Big Bear 4X4. It went in for it's 20 hour service the other day and I just got it back. I asked the service guy at the dealer if I would be able to run Castrol Sytec-Blend 20W-50 in my quad. He said that he didn't know if it would hurt the clutch at all. He said they use regular Castrol at the dealer and no Yamalube. I've run Castrol Syntec-Blend in my '86 Honda 350X for some time now, and I don't think it ever ran better or smoother in it's lifespan and I've never had a problem with my clutch. Any input will be greatly appreciated.

Adam, I have used both Castrol Syntec and Syntec blend in my 85 Honda BigRed and my 96 Timberwolf (which I have sold, I also use it in my 2000 Beartracker. I have found that Castrol is probably the best oil out there. I holds up great against heat and high rpms. It allows for smoother running and better shifting and will make your motor last a long time. My advice, for the machines sake, use the Syntec.
Happy trails, Shawn Jackow

Adam, I have used both Castrol Syntec and Syntec blend in my 85 Honda BigRed and my 96 Timberwolf (which I have sold, I also use it in my 2000 Beartracker. I have found that Castrol is probably the best oil out there. I holds up great against heat and high rpms. It allows for smoother running and better shifting and will make your motor last a long time. My advice, for the machines sake, use the Syntec.
Happy trails, Shawn Jackow

I know a guy who has been drag racing a Highly modified Suzuki 1200 Bandit and he swears by Castrol synthetic. Claims he never has trouble with clutch slippage. I have close to 20,000 miles on my 600 Bandit and have run Castrol synthetic (5w-50w) for the last 15,000 miles. Still running the original clutch with no problems.
Scott.