Product Description Helps Extend Engine Life in Cars with over 75 000 miles. Castrol GTX High Mileage is the premium part synthetic motor oil specifically formulated for vehicles with over 75 000 miles. As your engine ages gaskets become brittle seals deteriorate and oil consumption increases. Castrol GTX High Mileage is formulated with unique additive technology that combats this aging process and helps extend engine live by providing unsurpassed protection against sludge wear and oil burn-off.* * vs leading conventional oils 5W-30 tested Motor oil is made from crude oil and is used to lubricate clean and cool engines. Types of motor oil include conventional synthetic diesel bio-based hybrid (blends of conventional and synthetic) and recycled oils. Motor oil varies in weight and viscosity as well as additives that some manufacturers add to the oil during the refining process. A numerical code system created by the Society of Automotive Engineers (SAE) grades motor oils according to viscosity--the higher the number between 0 and 60 the more viscous (thicker) the oil is. Most consumer motor oils are graded by two numbers with the first number indicating cold weather (Winter or W ) performance. SAE 20W-50 This oil has a weight of SAE 20W-50 meaning it has an SAE viscosity rating of 20 in cold temperatures and a rating of 50 at normal operating temperature. Always check your vehicle s owner s manual to verify that this is the correct weight of motor oil for your vehicle. Conventional Motor Oil This oil is a conventional motor oil meaning it is refined from crude oil or petroleum products. Conventional motor oils may or may not have additives included after refining. Conventional motor oils are more versatile than synthetic or hybrid motor oils because they are suitable for use with nearly all types of modern vehicle engines from cars and trucks to motorcycles ATVs farm equipment and more. High Mileage Oil This oil is primarily designed for use in high-mileage cars and trucks including both older vehicles and new vehicles that see heavy long-distance use. Extra additives are included to minimize compression loss and to condition rubber seals and gaskets to prevent fluid leakage in older or high-mileage vehicles.