I have a 2007 Mach Z and have ran Ski Doo Syn oil in it from day one. I am being told by everyone (Except the Ski Doo dealer) that I can switch to Amsoil (like the Dominator), save a bunch of $$$ (hey more money for gas to ride)...the mechanics I speak with all tell me that the Amsoil is actually better, and that the sleds they tear down running the Amsoil are in the best shape (not sure why they are tearing down sleds in great shape but, hey that goes on another thread). I do not have a warranty on the sled but, don't need to do something stupid either...anyone switch? Did you have problems? Please let me know...thanks to all, keep to the right and keep the rubber side down!!!