I may be biased, being an AMSOIL dealer, but, everything I own, from weed eaters and mowers, to my RV all have AMSOIL. Been a dealer for 6 years. Increased fuel mileage(although sometimes minor) cooler operating temps and fewer breakdowns since. We use AMSOIL in my son's race bike. We tore the motor down after a season of Hare Scrambles. Engine is as clean as can be. I have sat here reading every single post on this tread. I will not argue about brands, but being in the business, I can tell you there are huge differences between brands and their quality. Not all oils are created equal. AMSOIL was the first to have a certified full synthetic motor oil. Most of the so called synthetics on the market today are not what they claim. I am also a shop owner and ASE certified auto technician for over 20 years.