Our most popular gear oil, 75W90 is the preferred product in nearly all car and light truck differentials, both conventional and limited-slip, as it contains friction modifier which is recommended for limited-slip units. Our 75W90 Gear Oil is common in racing differential applications and can be used in transmissions and transaxles; however, other Red Line lubricants have better frictional properties for rapid synchronization. Exceeds API GL-5.