Castrol AP Gear lubricants are multi-purpose, extreme pressure gear oils that are thermally stable and will provide transmission, differential and other application protection beyond that specified for SAE J2360 (Formerly MIL-PRF-2105E) requirements. This thermal stability extends oil service life and reduces critical component wear. They are recommended for make-up and complete refill of most passenger car and light truck conventional differentials, transmission and steering gears.