What is API GL 5?

API GL-5 is a performance specification established by the American Petroleum Institute for automotive gear lubricants, particularly for hypoid gears and other high-performance gear applications. It indicates that the lubricant provides superior protection against wear, oxidation, and foaming, and is designed to handle high loads and extreme pressure conditions. Oils meeting this specification are commonly used in manual transmissions, differentials, and axles. Additionally, API GL-5 oils often contain additives to enhance performance and protect gears under severe driving conditions.