5L SAE90 GL-4 Outboard Gear Oil SAE 90 Marine Lower Unit Gear Oil

SAE 90 GL-4 gear oil is a specialized lubricant formulated for the extreme pressure (EP) environments found within the lower unit of marine outboard motors. The lower unit, or gearcase, houses the pinion and propeller shaft gears, which are subjected to high-torque loads and constant immersion in water. The primary function of this lubricant is to maintain a protective film between the gear teeth, preventing metal-to-metal contact that would otherwise lead to rapid surface fatigue and catastrophic gear failure