Red Line Synthetic Oil Corporation has the most complete line of automotive lubricants available. Red Line realizes that reducing friction is necessary in a rear differential, but that friction is actually necessary in a transmission so that synchronization may occur. No lubricant can do a perfect job for both. The same is true for engines. Reducing friction is a goal of engine lubricants, but the detergents used in most motor oils compete with the friction reducers for the metal surface. So if you want the lowest friction, use an oil formulated for the lowest friction. Red Line manufactures Racing Oils which contain few detergents, so no compromise has to be made.