AMSOIL Long Life Synthetic 75W-90 Gear LubeAMSOIL Long Life 75W-90 Synthetic Gear Lube offers outstanding service in semi-truck, automotive and industrial applications. The value price, versatility and long service life of this synthetic 75W-90 makes it ideal for fleets.

AMSOIL Long Life 75W-90 package sizes include:
1-Quart Bottle (or buy case of 12)
1-Gallon Bottle (or buy case of 4)
5-Gallon Pail
16-Gallon Keg
30-Gallon Drum
55-Gallon Drum

Features and Benefits of AMSOIL Long Life 75W-90 Synthetic Gear Lube

  • Low cost per mile
  • Reduces friction for improved efficiency and performance.
  • Offers exceptional wear control
  • Ideal for extreme heat or cold weather
  • Conditions seals for reduced leaks

Designed for Long Service Life

This Long Life 75W-90 Gear Lube is formulated with shear stable, 100% synthetic base oil and backed up with robust anti-wear additives to provide long service life and resistance to deposit formation. The result is a service life of up to 500,000 miles (800,000 km) in semi-tractor differentials.

Extreme Temperature Performance

AMSOIL Long Life 75W-90 Synthetic Gear Lube flows down to -51°C (-60°F) providing superb cold weather performance and efficiency. In extreme heat, Long Life 75W-90’s synthetic makeup allows it to maintain steady viscosity and will not thin down, so protection is not compromised.

Applications for AMSOIL Long Life 75W-90 Synthetic Gear Lube

This product is ideal for differentials, manual transmissions and gear boxes where a 75W-90 or 80W-90 gear lube with the following industry specifications is suggested:

  • API GL-5
  • API MT-1
  • MIL-PRF-2105E
  • Dana SHAES 234 (for 250,000 mile or 400,000 km)
  • Dana SHAES 256 (for 500,000 miles or 800,000 km)
  • Eaton PS-037, PS-163
  • Mack GO-J & GO-J+
  • Meritor 0-76N
  • Navistar TMS 6

Service Life of AMSOIL Long Life 75W-90 Synthetic Gear Lube

Automotive Applications

Note: These service intervals do not apply in situations where water immersion occurs. Gear lube must be changed frequently under these conditions.

Normal Service

Change at 100,000 miles (160,000 km) or the interval as prescribed by the OEM (whichever is longer).

Severe Service*

Change at 50,000 miles (80,000 km). *Severe service can be described as racing, frequent towing, snow-plowing, hauling or frequently dusty conditions.

Heavy Duty Class 8 Truck

Change at intervals up to 500,000 miles (800,000 km) or follow the OEM recommendation for synthetic oil (whichever comes first).

Heavy Duty Off-Road

Follow the OEM recommendation for synthetic oil (whichever comes first). If these recommendations do not apply, change at twice the OEM oil change interval for conventional oil.

Limited Slip Differentials and AMSOIL Long Life 75W-90 Synthetic Gear Lube: Is a Friction Modifier Additive Needed?

AMSOIL Long Life 75W-90 Synthetic Gear Lube does contain limited-slip additives, but differential chatter can occasionally occur in some vehicles. As a precautionary measure, we recommend adding roughly two-thirds of a bottle of AMSOIL Slip-Lock Limited Slip additive or the counterpart OEM limited-slip differential additive.

Read more in our article: Does Friction Modifier Need to Be Added to AMSOIL Gear Lube in Limited-Slip Differentials

Mixing AMSOIL Long Life 75W-90 Synthetic Gear Lube with Other Brands

AMSOIL Long Life 75W-90 Synthetic Gear Lube is compatible with all other brands of conventional, semi-synthetic and synthetic gear oils. While you can safely mix AMSOIL Long Life Gear Lube with other brands, this will reduce the drain interval and performance capabilities of AMSOIL gear oil.

The use of any aftermarket oil additives (other than limited-slip friction modifiers) is definitely NOT recommended.


AMSOIL Long Life Synthetic Gear Lube 75W-90 (FGR)
Kinematic Viscosity @ 100°C, cSt (ASTM D-445)
Kinematic Viscosity @ 40°C, cst (ASTM D-445)
Viscosity Index (ASTM D-2270)
Brookfield Viscosity, cP (150,000 Max)
98,300 @ -40°C
Flash Point, °C (°F) (ASTM D-92) 150°C Min.
214 (417)
Pour Point, °C (°F) (ASTM D-97)
-51 (-60)
Copper Corrosion (ASTM D-130) 1b Max @ 121 °C (250°F) / 3hr
Falex Procedure B (ASTM D-3233) (failure load, lbf.)
Foam Stability (ASTM D-892) (20/50/20 maximum)
This value-priced synthetic 75w-90 is ideal for trucking, automotive and industrial applications. Designed for long service life and all-weather performance.
Manufacturer: AMSOIL
Model: Long Life 75W-90 Synthetic Gear Lube
Product ID: FGR