Max Gear Synthetic Oil 75w90 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 GL5 or GL4 fluid. MaxGear is an ultratough, high performance, GL5 automotive gear oil designed to provide maximum protection to heavily loaded gears while maximizing power output throughout the drive train. It outperforms other GL5 gear oils because it combines the highest quality synthetic oils with Royal Purple's proprietary Synslide additive technology. MaxGear makes gears run smoother, quieter, cooler and longer without overhauls. All viscosities of MaxGear are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives are necessary. MaxGear Synthetic Gear Oil is formulated to improve the efficiency of rear end assemblies and manual transmissions. Virtually eliminates both gear and bearing wear. API GL4 / GL5 Certified.