Description Reviews Max Gear is recommended for use in truck and automotive front or rear differentials, manual transmissions and lower gear units of marine engines that specify use of an API GL-5 or GL-4 fluid. It is non-corrosive to soft yellow metals (brass, bronze, copper, etc.) and synchronizer safe Max Gear is an ultra-tough, high performance automotive gear oil designed to provide maximum protection to heavily loaded gears while maximizing power throughout the drive train. Max Gear outperforms ordinary gear oils by combining the highest quality synthetic oils with Royal Purple’s proprietary Synerlec additive technology. Max Gear makes gears run smoother, quieter, cooler and longer without overhauls. Max Gear is formulated with a friction modifier additive – no additional additives are necessary. Performance Advantages: Maximizes horsepower Extends gear and bearing life Reduces operating temperature Severe service performance Lower coefficient of friction Superior corrosion protection Separates rapidly from water Meets warranty requirements Environmentally responsible Formulated for limited-slip differential use Note: You need 2 bottles for most R50/R52/& R53 Gen 1 cars. But if you're replacing your R50 early year trans (Midland) you will need 3 bottles to top it off correctly. You will also need 3 bottles to fill all Gen 2 cars.