Royal Purple ® Max Gear ® Oil is recommended for use in truck, motor home / RV, 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. Max-Gear ® is an ultra-tough, high performance, GL-5 automotive gear oil designed to provide maximum protection to heavily loaded gears while maximizing power output throughout the drive train. It outperforms other GL-5 gear oils because it combines the highest quality synthetic oils with Royal Purple's proprietary Synslide ® additive technology. Max-Gear ® makes gears run smoother, quieter, cooler and longer without overhauls. All viscosities of Max-Gear ® are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives are necessary.