Sierra Marine FC-W 4-stroke sterndrive engine oil has been formulated to provide excellent lubrication and corrosion protection. Stern drive and inboard engines operate under high-load and running stresses. This oil is developed for the marine environment and will out-perform standard 4-cycle automotive engine oils. It offers excellent detergency, anti-oxidants, anti-wear, and corrosion protection. Your engine will benefit with reduced wear to the internal components, protection of internal parts from corrosion, cleaner pistons, and prevention of ring sticking. Sierra Marine FC-W 4-stroke sterndrive engine oil also offers excellent low-temperature operating properties.