| One of the major benefits of running a synthetic motorcycle oil is its resistance to oxidation and thermal degradation, which inhibit the formation of sludge and deposits that contribute to increased wear. In the past, Harley-DavidsonŽ has defended use of its Genuine H-D Oil by arguing that oil breakdown in extreme heat is a non-issue because extreme heat conditions are not normally faced by motorcycle engines, while the superior cold-temperature benefits of synthetics also don't apply to Harleys. The fact is engine oil in Harley-DavidsonŽ motorcycles is subject to very high temperatures. Being air-cooled, Harley-DavidsonŽ engines get especially hot while idling in traffic, commonly reaching temperatures up to 240 degrees Fahrenheit. As heat and oxidation increase, so does viscosity, adversely affecting the lubricating qualities of the oil and increasing wear. The water, soot and acid byproducts of combustion also contribute to deposit formation. Harley-DavidsonŽ has stressed the importance of regular oil changes in order to remove these contaminants. Of course, promoting regular oil changes is also a good way to promote using petroleum-based Genuine H-D Oil. High-quality synthetic oils formulated with high-performance additives effectively withstand such contaminants, allowing motorcyclists to safely extend drain intervals. In support of their about-face and the introduction of a synthetic oil, Harley maintains that "the Motor Company has never supported the use of synthetic products in our vehicles because there has never been any test validations completed on the numerous formulations in HD/Buell motorcycles. This product has been exclusively designed for Harley-DavidsonŽ and is the only synthetic product TESTED and CERTIFIED by Harley-DavidsonŽ engineering for use in HD/Buell motorcycles." Although this is necessary marketing hype, Harley-DavidsonŽ V-twin air-cooled engines are not unique in their lubrication requirements and do not require a special Harley-only fluid. There is nothing about Screamin' EagleŽ Synthetic Motorcycle Oil that sets it apart from, or makes it better than, many other synthetic motorcycle oil formulations, except that Harley-DavidsonŽ is marketing it and directly profiting from the sales. According to Harley-DavidsonŽ, one of the unique benefits offered by Screamin' EagleŽ Synthetic Motorcycle Oil is its versatility. For the first time the company is recommending an oil that can be used in the engines, primary chaincases and transmissions of most Harley-DavidsonŽ motorcycles, including Evolution XL, Evolution 1340, Twin Cam 88 and 88B, Revolution and Buell models. This feature, however, is not unique. AMSOIL 20W-50 Synthetic Motorcycle Oil may also be used in the engines, primary chaincases and transmissions of these applications, providing superior lubricating protection in each component. How does Screamin' EagleŽ Synthetic Motorcycle Oil measure up to AMSOIL in wear protection? Four-Ball Wear Test results indicate that AMSOIL Synthetic Motorcycle Oil still provides the best protection possible for motorcycles. In fact, Screamin' EagleŽ Synthetic Motorcycle Oil leaves a wear scar nearly 80 percent larger than AMSOIL 20W-50 Synthetic Motorcycle Oil. Not only does AMSOIL Synthetic Motorcycle Oil offer greater wear protection than Screamin' EagleŠ Synthetic Motorcycle Oil, it also delivers greater value. Suggested retail price of Screamin' EagleŽ is nearly $2 a quart higher than AMSOIL 20W-50 Motorcycle Oil. And because AMSOIL Synthetic Motorcycle Oil may be used for extended drain intervals of up to twice the manufacturer's suggested interval, while Screamin' EagleŽ is recommended for standard drain intervals. AMSOIL customers realize additional savings. Harley-DavidsonŽ claims Screamin' EagleŽ Synthetic Motorcycle Oil has been "exclusively designed" for use in their motorcycles, pointing to extensive bench testing and over 230,000 miles of durability testing to back it up. AMSOIL INC. has 30 years of experience providing superior lubricating protection for all brands of motorcycles, and AMSOIL Synthetic Motorcycle Oils have been tested in millions of over-the-road miles. Testimonials from countless motorcyclists further demonstrate the superiority of AMSOIL Synthetic Motorcycle Oils. Formulated with top-of-the-line synthetic base stocks and high-temperature deposit control additives, AMSOIL Synthetic Motorcycle Oils provide superior protection and performance for motorcycles in all operating conditions. AMSOIL Motorcycle Oils effectively withstand oxidation and thermal degradation, keep wear to an absolute minimum, hold contaminants in suspension and keep engines running cool and clean. | 
laboratory testing has consistently revealed that Genuine H-D Oil does not provide the best protection possible for Harley-DavidsonŽ engines. In fact, Four-Ball Wear Tests show Harley-DavidsonŽ 20W-50 Motorcycle Oil leaves a wear scar over 50 percent larger than that left by AMSOIL Synthetic 20W-50 Motorcycle Oil.