Mercury High Performance Gear Lube is an exclusive formulation engineered to provide maximum protection and extended gear life in extreme conditions including high speed and high horsepower applications.. What this is: OEM SAE 90 High Performance gear lube for high-speed / high-hp gearcases.. Where it's used: Most Mercury, Mariner, Force outboards, jet pumps/Sport Jet 75+, and MerCruiser sterndrives.. Service cadence: Change annually or ~100 hrs (≈ 50 hrs in saltwater), and before storage.. You'