API GL-5 Gear Lubricants have high levels of extreme pressure (EP) additives that are particularly suited to hypoid gears in automotive axles operating under moderate speeds and loads. Additionally, these lubricants may be used in certain manual transmissions and trans-axles. They are not recommended for use in gearboxes / transmissions with yellow metal components. Please consult OEM specifications to determine which type of lubricant performance category your vehicle requires.

The American Petroleum Institute (API) has established a set of ratings to better distinguish between the unique physical and performance characteristics of different types of Gear Lubricants. Gearboxes and transmissions at work in heavy duty vehicles are subject to varying degrees of pressures, temperatures, and demands depending on make, model, and various other factors. Likewise, gear lubricants have unique specifications of their own - this potentially renders one exceptionally well-performing gear lubricant in one application useless or harmful in another.