AMSOIL SEVERE GEAR® 75W-110 100% SYNTHETIC GEAR LUBE

AMSOIL SEVERE GEAR 75W-110 100% Synthetic Gear Lube delivers extreme-pressure protection for differentials, manual transmissions, and transfer cases operating under punishing conditions. It is built for trucks, SUVs, heavy equipment, and commercial vehicles where towing, hauling, steep grades, and high ambient temperatures push conventional gear oils past their limits.

Modern drivetrains generate more torque and more heat than ever. Pickup trucks rated to tow 10,000+ pounds, Class 8 line-haul tractors running loaded through mountain passes, heavy equipment grinding through all-day cycles — these applications create gear contact pressures and operating temperatures that rapidly degrade conventional gear oils. When a gear lube loses viscosity or breaks down under heat, the result is accelerated wear, pitting, and scoring on gear teeth and bearings. A 75W-110 synthetic gear lube formulated for these extremes is not optional equipment. It is a maintenance requirement.

CONTROLS THERMAL RUNAWAY
Thermal runaway occurs when a gear lube cannot manage the friction-generated heat inside a differential or gearbox. As the oil thins from excessive heat, friction increases, which generates more heat, which thins the oil further. This self-reinforcing cycle can destroy gear sets rapidly. AMSOIL SEVERE GEAR 75W-110 is formulated to resist viscosity loss at elevated temperatures and maintain a stable lubricating film even under sustained high-load, high-heat conditions. By controlling thermal runaway, it inhibits the rapid lubricant degradation and component damage that follows. The viscosity index of 179 (ASTM D2270) confirms its ability to hold viscosity across a wide temperature range, from cold startups to sustained high-temperature operation.

IRON-SULFIDE BARRIER COATING FOR WEAR PROTECTION
Proprietary AMSOIL extreme-pressure additives form an iron-sulfide barrier coating directly on gear surfaces. This chemical film acts as a sacrificial layer that protects against wear, pitting, and scoring during the metal-to-metal contact events that are unavoidable in hypoid gears, ring-and-pinion sets, and heavily loaded bearings. The 75W-110 viscosity grade provides a thicker oil film than a 75W-90 at operating temperature — 20.5 cSt kinematic viscosity at 100°C versus 16.0 cSt for the 75W-90 (ASTM D445) — while still flowing well at low temperatures. For applications like a Ford Super Duty rear differential under heavy trailer loads or a GM 2500HD towing through summer heat, that additional film thickness reduces metal contact and extends component life.

EXCELS IN TEMPERATURE EXTREMES
SEVERE GEAR 75W-110 resists breakdown from high heat, preventing the formation of acids, carbon deposits, and varnish that contaminate gear oil and shorten seal life. Its wax-free synthetic construction also improves cold-flow properties. The Brookfield viscosity at -40°C is 86,140 cP (ASTM D2983), well within the requirements for cold-weather operation in the 75W range. The pour point of -43°C/-45°F (ASTM D97) means it flows freely even in extreme winter conditions. This wide operating range makes it suitable for vehicles that tow in desert heat during summer and sit in subzero temperatures overnight in winter.

LONG OIL, SEAL, AND EQUIPMENT LIFE
Because it resists thermal and oxidative breakdown, SEVERE GEAR 75W-110 extends both oil life and the life of the seals and gears it protects. It is compatible with conventional and synthetic gear oils, and it contains friction modifiers for limited-slip differential applications. For differentials that require additional limited-slip friction modifier beyond what is built into the oil, AMSOIL Slip Lock can be added. The flash point of 218°C/424.4°F (ASTM D92) reflects its high thermal stability and resistance to volatilization at elevated sump temperatures.

REDUCES DIFFERENTIAL OPERATING TEMPERATURES
Lower friction means less wasted energy converted to heat. SEVERE GEAR 75W-110 is engineered for better friction and heat reduction compared to conventional gear oils, which translates directly to lower differential operating temperatures under load. Lower temperatures slow the rate of oil degradation, reduce seal hardening, and contribute to improved fuel economy — particularly noticeable in drivetrains that spend long hours under sustained load.

Specifications and Compatibility
AMSOIL SEVERE GEAR 75W-90, 80W-90, 75W-110, and 75W-140 meet the following specifications: API GL-5, MT-1, MIL-PRF-2105E, Dana SHAES 234 (formerly Eaton PS-037), and Mack GO-J. They can also be used in axles where an API GL-4 lubricant is recommended. The 75W-110 grade is suited for differentials, manual transmissions, and other gear applications from manufacturers including Ford, GM, and Chrysler that specify GL-5 based gear lubricants. It is compatible with most limited-slip differentials. AMSOIL does not support extended drain intervals where water contamination occurs or where oils have been mixed with non-AMSOIL products. Aftermarket oil additives other than those specified by AMSOIL are not recommended for use with AMSOIL gear oil.

Service Life
For cars, SUVs, and light trucks in normal service: drain at 100,000 miles (161,000 kilometers) or according to the owner's manual, whichever is longer. For severe service: drain at 50,000 miles (80,500 kilometers) or according to the owner's manual, whichever is longer. For heavy-duty Class 8 line haul: follow the OEM drain interval for synthetic oil up to 250,000 miles (402,500 kilometers) or three years, whichever comes first. For vocational/delivery applications: follow the OEM drain interval for synthetic oil up to 120,000 miles (193,200 kilometers) or three years, whichever comes first. For heavy-duty off-road: follow the OEM drain interval for synthetic oil up to 100,000 miles or two years, whichever comes first. Gear oils should be changed more frequently when operating in dusty or dirty conditions, unless the gear system is properly sealed and equipped with membrane-type breathers.