Clean oil is essential in reducing friction and preventing damage to internal components providing many years of engine life. Engineered for sterndrive and outboard applications this 4-stroke 10W-30 marine oil has been extensively tested to ensure impressive protection against corrosion and wear. Features premium-grade synthetic and mineral-based stocks exceeding all marine industry 4-stroke oil requirements including FC-W and FC-W Catalyst Compatible. The Quicksilver brand is the leader in delivering uncompromising engine oils parts and accessories to the marine industry for over 65 years. Quicksilver is the premier supplier of Mercury Marine Original Equipment replacement engine parts oils and accessories but also works to serve all Original Equipment brands in the marine and powersports industries. It has earned a loyal following by providing the highest quality products that are tested through some of the most rigorous environments and testing procedures. No aftermarket company comes close to the level of research and design as Quicksilver; buying Quicksilver is buying performance protection and peace of mind.