Full Synthetic Marine Gear Lube 5 Gallon | Sierra 18-9680-5Full Synthetic Marine Gear Lube 5 Gallon Sierra 18 9680 5 Sierra 5 Gallon Full Synthetic Marine Gear Lube 18 9680 5 Sierra's full synthetic lower unit gear lube optimizes gear life by reducing friction while providing wear protection in severe operating conditions. Sierra full synthetic gear lube Engineered to protect gears, bearings, and internal gearcase components of outboards and stern drives under high load operating conditions Formulated for use