TESTED-CERTIFIED for use in Harley-Davidson engine, primary chain case and transmission applications, Screamin' Eagle SYN 3 fully synthetic oil makes topping off fluids a simple, one-product process. Developed with a proprietary three synthetic base stock formula, SYN 3 is formulated to provide for long-term protection and engine cleanliness requirements, and to provide superior high-temperature protection for high-output engines. This formula is approved by Harley-Davidson for use in all stages of engine, chain case and transmission life.