The Castrol 10W30 EDGE with SYNTEC motor oil is a unique and proprietary formula that reduces volatility and provides superior protection for critical engine parts helping your car to function optimally at maximum power. Castrol EDGE with SYNTEC neutralizes acids in your engine that can cause rust and corrosion on vital engine parts such as cylinders, bearings and hydraulic valve lifters as well as providing stability and endurance under extreme conditions (heat, load, speed) that can cause conventional oils to break down. Best of all, EDGE can be used with confidence in every gasoline-engine passenger car, new or old, regardless of oil previously used.