A friend of mine who races used to change the oil after every race switched to Amsoil and ran the oil for one racing season. He needed to do some upgrades to the engine. When they opened it up everything looked brand new. The cylinder walls look like they had just been honed, no visible wear. To say the least he was surprised. Also he's my mechanic and one of the few who I trust when it come to working on any of my vehicles. I started using Amsoil 20-50 in the Harley 2 years ago and will continue. If I ever switch to synthetic on the 911 Amsoil will be at the top of the list.
