Amsoil Synthetic Gear Lubes

Vehicles are continuing to advance, to produce more horsepower, torque and towing capacity, however, these gears and bearings responsible for converting this increased power into wheel rotation have remained largely unchanged. Also, the volume of gear lube available to cool and protect has also been reduced to improve fuel economy and reduce drag. Amsoil synthetic gear lubes are increasingly relied upon to meet these higher demands.

Increased Wear Resistance

Differential designs come with inherent suffering points. In a traditional automotive differential, the input pinion gear concentrates intense pressure on the ring gear, forcing it to turn the side and spider gears. As all the gear teeth mesh, they slide against one another repeatedly, separated only by a microscopic film of lubricant. The constant stress the lubricant film bears can shear lesser gear lubes, causing permanent viscosity loss. Once sheared, the fluid film weakens, ruptures and allows metal-to-metal contact, leading to increased friction, accelerated wear and eventual gear and bearing failure.

It’s here that synthetics prove their worth. Conventional lubes formulated with viscosity index (VI) improvers shear more readily under stress. AMSOIL synthetic gear lubes, however, maintain viscosity better than conventional and other synthetic gear lubes despite rigorous use and contain advanced antiwear additives for further protection.

Temperature Extremes

Differentials have always run hot, but increases in power and torque coupled with reduced fluid volume and reduced airflow due to improvements in vehicle aerodynamics only worsen the problem. As temperatures in the differential climb, conventional gear lubes tend to lose viscosity. Extreme loads and pressures can break the lubricant film, causing increased metal-to-metal contact and heat. This increased friction and heat cause the lubricant to lose even more viscosity, further increasing friction and heat. This friction/heat cycle continues spiraling upward in a vicious cycle known as thermal runaway, which eventually leads to higher wear and irreparable equipment damage.

Conventional gear lubes also tend to leave behind deposits that coat gears and bearings, inhibiting heat transfer and shortening their life spans. What’s more, they tend to thicken and increase internal drag and reduce fuel economy.

AMSOIL synthetic gear lubes, however, are engineered in a lab and contain only uniform molecules less prone to volatilizing at high temperatures. By design, they resist breakdown from high heat to provide better cooling and protection against acids and carbon/ varnish formation. Their wax-free construction also improves cold-flow properties, improving fuel economy and cold-weather shifting. As the graph at right shows, AMSOIL SEVERE GEAR® Synthetic Gear Lube delivers 20 percent more cold-temperature protection than required by the industry standard.

Extreme-Pressure Additives

Many drivers operate under severe-service conditions without even knowing it. Towing, hauling, steep-hill driving, commercial use, plowing, racing, off-road use, rapid acceleration, frequent stop-and-go operation and high ambient temperatures all can place even greater stress on gears and bearings. The sliding motion and pressure on gears can wipe the lubricant away, particularly in spiral-cut hypoid gears. AMSOIL SEVERE GEAR contains extreme pressure (EP) additives that form a durable iron sulfide barrier on gear and bearing surfaces to guard against metal-to-metal contact and defend against pitting and scoring in even the harshest driving conditions.

Extended Drain Intervals

Following the original equipment manufacturer (OEM)-recommended differential drain interval using the OEM-recommended fluid can get very expensive. Plus, the synthetic gear lubes recommended by OEMs are often more costly themselves. AMSOIL SEVERE GEAR® is recommended for 50,000 miles (80,467 km) in severe service. The extended-drain capabilities and superior performance and protection of AMSOIL synthetic gear lubes make them a prime choice for customers looking to add to their bottom line.


SEVERE GEAR 100% Synthetic Extreme-Pressure (EP) Gear Lube           

  • Formulated for the severe operating conditions of today’s pick-up trucks, SUVs, heavy equipment and other hard-working vehicles
  • Advanced protection against wear, even with up to 15 percent water contamination1
  • Controls thermal runaway • Protects against rust and corrosion • Helps reduce operating temperatures
  • Maximum efficiency
  • Long oil, seal & equipment life
  • Flexible easy-pack for clean, fast installation


   SEVERE GEAR SAE 250                                                                                 

  • Premium-grade, extreme-pressure gear lube engineered specifically for high-load demands
  • Shear stable in extreme temperatures
  • Provides cushion between metal surfaces that absorbs impact to prevent pitting, scoring and wear
  • Excellent for severe racing applications subject to shock loading, steep angles, high pinions, G-forces and lubricant sling-off

75W-90 Long Life Synthetic Gear Lube                                                                       

  • Specifically engineered for 500,000-mile (805,000-km) service life in over-the-road trucks
  • High-load gear and bearing protection
  • Protection against rust and corrosion
  • Better cold-weather shifting • Improved efficiency
  • Improved seal life