Gear Oil Additive is added to the gear oil - mixing takes place automatically during operation. The product is suitable for both mineral and synthetic gear oils. 50g) Gear Oil Additive is sufficient for 2.5 liters (2.64 U.S. QT) of gear oil. Minimum oil filling of liter (1.05 U.S. QT) is requested for optimum product performance. Not suitable for automatic transmissions.