Mobil 1 15W-50 Synthetic Motor Oil is back by popular demand! Mobil 1 15W-50's high viscosity provides outstanding performance in high-revving, high-temperature conditions. Mobil 1 15W-50 exceeds warranty requirements for gasoline engines where an API certified oil is specified. It meets: API SM/SL, Requirements for Diesel Powered Vehicles where an API CF or API CD is recommended, and provides extra anti-wear additive for older vehicles. Mobil 1 15W-50 is formulated with supersyn, an extra-high viscosity synthetic fluid, plus extra anti-wear additive to provide extra protection for severe service applications such as towing, hauling and racing. Mobil 1 15W-50 is recommended for high performance vehicles including turbocharged and supercharged engines where a thicker oil film is desired. Also recommended for older valve train designs that may benefit from a higher level of anti-wear normally not required for newer generation vehicles. Mobil 1 15W-50 will also provide better anti-wear protection for higher valve spring tensions in certain racing engines. Mobil 1 15W-50 is the most advanced performance synthetic engine oil designed to provide the cleaning power, wear protection and performance reserve to keep engines running smooth and clean.