I have 32 hours on my 09 450 YZ. My question is, does Yamaha have a specific oil for the shock like they have for the front forks? I have the $25 a bottle KYB S1 oil for the forks and was real happy. Worked just like new. What do you use for the rear? I assume pressure is 148 psi like all the other KYB stuff. While I am on the subject of rear shocks, at 32 hours (never in mud), should I also replace the foam bumper? They bike only seen races on race day. no midweek practice ever.