Quicksilver High Performance SAE 90 Gear Lube – Maximum Protection for High-Power Engines

Quicksilver High Performance SAE 90 Gear Lube is engineered to provide unrivaled protection for gearcases in the most powerful marine engines. It is recommended for all outboards and sterndrives above 75 HP, where standard oils may not withstand the extreme stress. High Performance’s formula includes special additives that create an exceptionally strong oil film and prevent metal-on-metal contact between gear teeth, even at very high RPM and during sudden shock loads. This dramatically reduces wear and the risk of gear tooth breakage or failure, significantly extending the life of the lower unit.

In addition to wear protection, this oil contains enhanced anti-corrosion and anti-foam additives that protect the gearcase even if water intrudes. On high-horsepower, high-speed engines, it’s possible for small amounts of water to enter through seals during extended operation. High Performance Gear Lube is formulated to retain its properties in the presence of water and to prevent the “foaming” effect that can break the oil film. Thus, the oil protects gears from damage due to water contamination and guards the gearcase against rust.

This oil is the product of decades of Mercury Marine’s experience and engineering – the company designed the gearcases this oil protects, so High Performance Lube is perfectly tuned to the needs of those systems. Compared to Premium Gear Lube 80W-90 (which is for lower horsepower), High Performance SAE 90 has higher load-carrying capacity and shear stability, intended for big V6/V8 engines, racing boats, offshore runs, etc., where loads are extremely high. This oil can even prevent catastrophic gearcase failures that might occur in extreme conditions, thanks to its ability to maintain lubrication even with small amounts of water – often a key factor in avoiding lower unit seizure.

Typical use cases:

• Outboard engines above 75 HP – including heavy-duty V6 (e.g., 150–300 HP) and V8 outboards by Mercury, Yamaha, Suzuki, etc., that operate under high load
• Sterndrive & inboard drive systems (MerCruiser Bravo One/Two/Three, Volvo Penta, etc.) where the manufacturer requires or recommends High Performance/HP gear oil – especially for high speeds or saltwater operation
• Racing and high-speed boats that frequently run at full throttle – High Performance Lube will protect the gearcase during prolonged high-speed runs and moments of extreme torque
• Large offshore fishing boats, charter vessels, and other commercial boats with powerful engines, where transmission reliability during long operations is paramount
• Any situation where standard 80W-90 oil shows signs of breakdown (e.g., discoloration, burnt smell, metal shavings) under heavy use – switching to Quicksilver High Performance Gear Lube provides extra safety margin and performance

Usage & Change Instructions:

• The procedure for changing to Quicksilver High Performance Gear Lube is similar to standard: remove the lower and upper plug, drain the old oil, fill from bottom up with a pump until it overflows from the top hole. Install the top, then bottom plug, using new washers for sealing.
• Due to the higher viscosity (SAE 90), ensure the engine is upright (vertical) when filling to avoid air pockets. The viscous oil needs a bit more time to fill all cavities – don’t rush; when you see oil at the top vent, wait a minute or two, then pump a little more before closing.
• Inspect the old drained oil: if you’re switching to High Performance from Premium, you might notice fewer metal particles in subsequent changes as the oil protects better. Still, fine metallic on the magnet plug is normal.
• Change it at least once a year or every 100 hours (whichever comes first) under normal conditions. For racing or extreme use – even more frequently, say every 50 hours or at the start of each racing season. Fresh oil is the cheapest insurance against gearcase damage.
• Do not mix High Performance with other oils – if transitioning from regular 80W-90 or another oil, drain out the old completely. High Performance Lube has a specific additive system that works best on its own. Mixing won’t cause harm, but can dilute its peak properties.
• Keep the container tightly sealed and store any leftover oil in a dry place. Ensure no contaminants enter the bottle when refilling the pump – even small grit can cause wear if it gets into the gearcase.
• After changing, initially monitor the gearcase for leaks or changes in sound – High Performance may make the gearbox run quieter due to better protection. If you hear abnormal noises, check levels and for any leaks (in case a washer isn’t sealing properly).
• Important: If during operation you notice a milky emulsion on the plug or significant cloudiness in the oil, that’s a sign of water intrusion. High Performance Lube will cope better than regular oil, but that indicates you should replace seals as soon as possible to avoid serious damage.