Modern differentials handle more heat and stress than ever before. AMSOIL SEVERE GEAR® Synthetic Gear Lube protects against the devastating effects of high-heat, severe-service operation.

Your vehicle’s differential is likely not top of mind while hauling snowmobiles or ATVs for a fun weekend on the trails. Unfortunately, towing is in the severe service category and places extreme stress on your drivetrain. Today’s vehicles produce substantially more horsepower, torque and towing capacity than their predecessors, yet the design of differential gears and bearings remains largely unchanged. Many differentials even use less gear lube and lower viscosities than before in an effort to reduce drag and increase fuel economy. In essence, less gear lube is responsible for providing more protection.

Fighting the Grind

Differential designs have inherent weaknesses. In a traditional automotive differential, the pinion gear concentrates intense pressure on the ring gear. As the gear teeth mesh, they slide against one another, separated only by a thin layer of lubricant. The repeated stress the lubricant film bears can shear inferior gear lubes causing permanent viscosity loss. Once sheared the fluid film weakens, ruptures and allows metal-to-metal contact, eventually leading to gear and bearing failure. The situation is amplified by severe-service applications like towing.

Forgotten Gears:  Approximately 22 components make up the average differential. To operate efficiently they require clean, properly formulated gear oil, yet maintenance is often overlooked.

Thermal Runaway

The extreme pressures and temperatures placed on gear lubricants can lead to a serious issue called
thermal runaway. As temperatures in the differential climb, some gear lubes lose viscosity and load-carrying capacity. When extreme loads break the lubricant film, metal to metal contact occurs, increasing friction and heat. This increased friction and heat, in turn, results in further viscosity loss, which further increases friction and heat. As heat continues to spiral upward, viscosity continues to spiral downward. Thermal runaway is a vicious cycle that leads to irreparable equipment damage from extreme wear, and ultimately catastrophic gear and bearing failure.

AMSOIL SEVERE GEAR Synthetic Gear Lube

SEVERE GEAR excels in protecting gears and bearings from the rigors of severe-service operation. By design, it resists breakdown from high heat, preventing acids and carbon/varnish formation. Its wax-free construction also improves cold flow properties improving fuel economy and cold-weather performance.

AMSOIL SEVERE GEAR product features and benefits

• Superior film strengthAMSOIL SEVERE GEAR Synthetic Gear Lube
• Controls thermal runaway
• Protects against rust and corrosion
• Helps reduce operating temperatures
• Maximum efficiency in all climates
• Long oil, seal and equipment life
• Flexible easy-pack for clean, fast installation
The key is to understand the importance of differential maintenance and recommend gear oil changes. AMSOIL SEVERE GEAR Synthetic Gear Lube is multi-functional and formulated for the applications of your cars, trucks and other equipment that is placed under heavy stresses.
Follow the vehicle owner’s manual recommendations for initial (break-in) gear oil change. Consult the AMSOIL product guide for the proper recommendations for your vehicles.
To purchase AMSOIL SEVERE GEAR synthetic gear lube follow this link:
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The new AMSOIL SEVERE GEAR easy-pack helps the easy of changing differential fluid by reducing mess and saving time. The AMSOIL Easy-Pack Gear Lube packaging is an innovative first for gear lube maintenance. No more spilling, no more looking around for a pump and other devises to try to get the gear lube into your differentials.


The specialty shop that rebuilt my Ford* F-150’s* rear-end said to use it if I didn’t want to see him again. I have not been back and its been 4 years of hard towing of a camp trailer. I can say it stays clean like no other oil I have used.
Mayberry, Vacaville, CA