I switched two cycle oil because I could not find Amsoil series 2000 racing oil any more . My local motorcycle shop stopped carrying it because of a few high performance sled engine failures. They recommended Redline snowmoble synthetic oil which you can premix. The cost is less than I was paying for the Amsoil. They use this oil in all of their modified HP engines. My trimmer, blower and Suzuki Proline all increased power output, a very noticeable power increase, also everything is running smoother.