use mobil1 or oem fluids. royal purple is junk. Castrol edge? again, breaks down quick! and amsoil? cmon, cut the SH*T! the most overrated oil and fluids on the market and they cost too much. mobil1 was just having a corporate sale at $5 a quart. beat that. I've used them all. nothing beats mobil1. period. used amsoil in Yamaha sled for a season. went back to yamalube and the thing ran way better, like night and day. used amsoil in my Yamaha yz426. ahhh, again, was disappointed. could hear the engine making noises it had never made before. before you say I don't know anything, I have been in this game for years and have had many cars, trucks and toys. would not recommend anything but mobil1. wish I was paid to say this, but i'm not. one of the best race shops in the east mike deez in Seekonk, RI... proof in the pudding. hes dynoed all kinds of autos, and has never seen anything work or produce the constant horsepower that mobil1 does. nuff said.