Quicksilver SAE 90 high performance gear lube provides the proper corrosion protection and lubrication needs of marine gear cases not found in automotive based oil. This gear lube provides maximum protection against water intrusion and wear. Mercury recommends the gear lube be changed at least once per year (prior to storage) or every 100 hours of operation. See your owners manual for specific recommendations. 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.