The Mercury Extreme Performance Gear Lube 85W-90, part number 8M0111677, is Mercury Marine's premium gear lubricant developed specifically for high-performance outboard and sterndrive applications.
 
Designed for racing, offshore, and severe-duty service, it provides exceptional protection for gears, bearings, driveshafts, and propshaft assemblies operating under extreme loads, high RPM, and elevated temperatures.
 
For performance boaters, gearcase reliability starts with proper lubrication. Every horsepower produced by the engine passes through the lower unit, making gear lube one of the most important maintenance items affecting performance, durability, and operating life.
 
Why Mercury Extreme Performance Gear Lube Is Different
 
Unlike conventional marine gear oils, Mercury Extreme Performance Gear Lube is formulated specifically for high-load gearcases found in Mercury Racing and high-horsepower Mercury Marine applications.
 
The advanced formula contains extreme-pressure additives that help maintain a protective lubricant film between gear teeth under severe operating conditions. This reduces metal-to-metal contact, minimizes gear tooth wear, and helps protect bearings from surface fatigue and overheating.
 
The lubricant is also engineered for exceptional shear stability. As gears mesh under heavy loads, lower-quality lubricants can lose viscosity and film strength. Mercury's Extreme Performance formula is designed to maintain protection under sustained high-speed operation where gearcase temperatures and loads can become extreme.
 
Another advantage is its ability to provide additional protection in the presence of minor moisture contamination. Advanced emulsifiers help maintain lubrication properties if small amounts of water enter the gearcase through aging seals, providing an added margin of protection until repairs can be made.
 
Designed for Mercury Racing Gearcases
 
Mercury Racing developed this lubricant for applications where gearcase durability and efficiency are critical. It is commonly used in Sportmaster, CLE (Crescent Leading Edge), TorqueMaster, Fleetmaster, SSM #4, SSM #6, and numerous offshore and racing lower units.
 
Whether running sustained high speeds offshore, accelerating hard in drag racing competition, or operating at elevated RPM in tunnel boat racing, proper lubrication is essential for maximizing gear and bearing life.
 
Broad Mercury Racing & Mercury Marine Fitment
 
Mercury Extreme Performance Gear Lube is commonly used in Mercury Racing Formula 1 2.0L, SST-120, SST-140, S3000, 245 Carb, 260 EFI, 280 ROS, 300 ROS, 300 Drag, 300X, 300XS, and numerous offshore racing and custom performance applications.
 
It is equally popular in Mercury Marine XR2, XR4, XR6, XRi EFI, Laser EFI, 150 HP, 175 HP, 200 HP, 220 Laser EFI, 225 HP, 225 Pro Max, 250 EFI, 250XB, Optimax, Pro XS, and other high-performance V6 outboards equipped with Sportmaster, CLE, Fleetmaster, and TorqueMaster gearcases.
 
Mercury's modern Racing lineup also relies on premium gearcase lubrication. Common applications include the 250R, 300R, 400R, 450R, and 500R platforms, along with Mercury Racing's latest competition engines, including the APX 200, APX 250, and 360 APX Formula 1 outboards used in professional tunnel boat racing and international competition.
 
A Small Investment That Protects Expensive Components
 
A complete gearcase rebuild can cost thousands of dollars in gears, bearings, seals, driveshafts, propshafts, and labor. Gear lubricant is one of the least expensive maintenance items on the boat, yet it directly affects the lifespan of every internal component.
 
Regular gear-lube changes also provide an opportunity to inspect for water intrusion, metal particles, bearing wear, and other early warning signs before they become major failures. Many racers and performance boaters inspect and replace gear lube more frequently than standard maintenance schedules because of the relatively low cost compared to gearcase repairs.
 
Final Thoughts from Buckshot Racing #77
 
The Mercury Extreme Performance Gear Lube 85W-90 (8M0111677) remains the benchmark lubricant for Mercury Racing and high-performance Mercury Marine gearcases. With advanced extreme-pressure additives, excellent shear stability, high-temperature protection, corrosion resistance, and water-tolerance characteristics, it is specifically engineered for the demands of modern performance boating.
 
Whether you're running a Formula 1 tunnel boat, APX competition outboard, 300 Drag, 280 ROS, 300R, 400R, 500R, 300X, Pro Max, Optimax, or a Sportmaster-equipped lake boat, Mercury Extreme Performance Gear Lube provides the protection needed to help maximize gearcase life, reliability, and performance.