I hate to sound like a traitor but I have been running Honda Pro4 Synthetic Blend. But, my freind has an r-450, I don't know if you guys have heard about the wierd tranny wine they have been having but his sounded awful when it was doing it. He went to his forum and asked what to do about it and some said new engine cases were and back order that were supposed to stop the wine and others had just switched to royal purple oil. He switched and has had no wine since. Just so you know he tried other semi synthetics before royal purple to no avail but he switched to it and the tranny hasen't made a peep. I figure if it is good enough to do that I might as well try it so I am going to pick some up and try it after my next race. I don't want to change before and run into some type of problem. I race next sat so after that I will change to royal purple and install my DASA MX Grind Cam and let all you guys in on how it turns out.