Modern turbo diesel pickup trucks, V-10 gasoline pickups and sport utility vehicles (SUVs) and high-horsepower V-8 trucks boast more towing and payload capacities than ever before.
The extreme loads, pressures and temperatures experienced by modern vehicles place increased stress on gear lubricants that can lead to a serious condition known as thermal runaway. As temperatures in the differential climb upward, gear lubricants tend to lose viscosity, while extreme loads and pressures can break the lubricant film, causing increased metal-to-metal contact and heat. The increased friction and heat, in turn, cause the lubricant to lose further viscosity, which further increases friction and heat. As friction and heat increase, lubricant viscosity decreases. As viscosity decreases, friction and heat continue to spiral upward. The hotter it gets, the hotter it gets. It is a vicious cycle that eventually leads to greatly increased wear and irreparable equipment damage.
AMSOIL Severe Gear® Synthetic Extreme Pressure (EP) Gear Lube features an exclusive blend of high viscosity, shear stable synthetic base oils and an extra treatment of high-performance additives that provide a highly protective iron sulfide barrier coating on gear surfaces. Severe Gear Synthetic Gear Lube effectively protects equipment from thermal runaway through superior viscosity protection.
Viscosity is the most important property of a lubricant in its defense against friction and wear. Viscosity correlates to film strength, and it is film strength that keeps moving parts from contacting each other and creating friction, heat and wear. The higher the viscosity of a lubricant, the greater protection it provides. AMSOIL Severe Gear Synthetic Gear Lube is available in 75W-90, 75W-110, 75W-140, SAE 190 and SAE 250 viscosities, each providing superior protection through superior film strength.
As temperatures rise, gear lubricant viscosity and load-carrying abilities decrease. A lubricant’s viscosity index (VI) indicates its ability to maintain its protective viscosity in high-temperature service. The higher a lubricant’s VI, the less its viscosity changes in temperature extremes.
AMSOIL Severe Gear Synthetic Gear Lube provides a high viscosity index, allowing it to protect against thermal runaway by maintaining its superior viscosity protection in high-temperature service.
Many gear lubes are formulated with viscosity index (VI) improvers in order to ensure multi-grade viscosity protection in both hot and cold temperatures. VI improver additives keep lubricants from becoming too thick to flow in cold temperatures and too thin to protect in high temperatures. However, shearing forces within equipment can cause these additives to break down and lose viscosity.
AMSOIL Severe Gear effectively protects against thermal runaway by maintaining its protection qualities, even in severe, high-shear operating conditions.
The superior viscosity protection, viscosity index and shear-stability properties of AMSOIL Severe Gear Synthetic Gear Lube effectively protect equipment from the devastating effects of thermal runaway. Severe Gear Synthetic Gear Lube is ideal for severe-duty applications, including towing, hauling, steep hill driving, commercial use, plowing, racing, off-road use, rapid acceleration, frequent stop-and-go operation and high ambient temperatures.