Like an engine, a differential casing must have oil inside in order to operate. An LSD creates more heat than standard differentials therefore the right oil must carefully be considered. For daily driving conditions, the differential oil should be changed once every two engine oil changes. For aggressive driving, the differential must be changed more frequently. Cusco provides three types of LSD oil. The Cusco Mission Oil (75W-85) is recommended for FF or 4WD (front) applications. For FR and 4WD (rear) applications, as well as midship cars, the Cusco LSD Oil (80W-90) is the right choice. For long, and endurance type racing on FR, 4WD (rear), the Cusco LSD Oil Super 140 (80W-140) is recommended. This oil is also recommended for those who want to increase sensitivity of their LSD too.