An outboard's operating conditions are so different, that special levels of certification exist for marine engine oils: FC-W® (four stroke). These represent the minimum standards of the National Marine Manufacturer's Association® (NMMA®) for marine engines. Yamalube 4M outboard engine oils meet or surpass these requirements. Featuring a proprietary blend of marine-specific anti-wear additives, shear-stable polymers, corrosion inhibitors, detergents, dispersants, and viscosity index improvers, they're superior to automotive oils in their protection, durability, and corrosion resistance. Whatever oil you choose for your outboard, make sure it is the correct type and viscosity and that it carries the NMMA® FC-W® label.