AMSOIL 80W-90 Synthetic Gear LubeSome differentials and gear boxes specify the use of 80W-90 EP (extreme pressure) gear oil. offers a premium synthetic upgrade in AMSOIL Synthetic 80W-90 Gear Lube. This gear lube delivers high load capacity, long service life and the ability to withstand both extreme cold and hot operating conditions. For applications requiring the API GL-5 specification along with many others.

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 or 55 – US Gallon Drums

Features and Benefits of AMSOIL 80W-90 Synthetic Gear Lube

  • Lowers friction for optimized fuel mileage
  • Steady wear protection
  • Withstands extreme hot or cold operation
  • Keeps seals pliable to prevent oil leaks
  • Long life formula

Supreme Wear Protection

This synthetic 80W-90 gear oil is designed to prevent wear from every angle. AMSOIL starts with a shear-resistant base oil and then reinforces it with tireless extreme pressure additives. AMSOIL 80W-90 Synthetic Gear Lube maintains its viscosity under the stress of extreme heat and heavy loads. It is resistant to thinning and shear down, so vital components are always protected, even during long periods of severe service.

Amazing Cold Weather Performance

AMSOIL 80W-90 Synthetic Gear Lube flows down to -42°C (-44°F), so equipment operates smoothly and receives instant oil protection. Efficiency and performance remain constant, regardless of the weather.

Keeps Seals Pliable

Don’t buy into the old wives tale that synthetic gear lubes can somehow cause oil leaks. Today’s synthetic gear oil technology from AMSOIL actually keeps seals pliable and supple far longer and more effectively than regular gear lubes.

Applications for AMSOIL 80W-90 Synthetic Gear Lube

This product is ideal for differentials, manual transmissions, transfer cases and gear boxes suggesting the following industry specifications where an 80W-90 gear lube is suggested:

  • API GL-5 (can also be use in gear boxes requiring API GL-4)
  • API MT-1
  • MIL-PRF-2105E
  • Dana SHAES 234 (for 250,000 mile or 400,000 km)
  • Eaton PS-037, PS-163
  • Mack GO-J
  • Arvin/Meritor 0-76D

Service Life of AMSOIL 80W-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.

Commercial Truck

Change at the OEM recommendation for synthetic oil up to 120,000 miles (190,000 km) to a maximum of 3 years.

Heavy Duty or Off-Road Service

Change at the OEM recommendation for synthetic oil up to 100,000 miles (160,000 km) to a maximum of 2 years.

Limited Slip Differentials and AMSOIL 80W-90 Synthetic Gear Lube: Is a Friction Modifier Additive Needed?

AMSOIL 80W-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 80W-90 Synthetic Gear Lube with Other Brands

AMSOIL 80W-90 Synthetic Gear Lube is compatible with all other brands of conventional, semi-synthetic and synthetic gear oils. While you can safely mix AMSOIL 80W-90 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 80W-90 Synthetic Gear Lube

SAE 80W-90

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) @-26°C

46, 200

Flash Point °C (°F) (ASTM D 92)


Pour Point °C (°F) (ASTM D 97)

-42 (-43.6)

Falex Procedure B (ASTM D-3233) (failure load, lbf.)


Foam Stability (ASTM D-892) (20/50/20 maximum)


A synthetic extreme pressure 80W-90 gear lube for cars or trucks that require an oil with the API GL-5 specification.
Manufacturer: AMSOIL
Model: 80W-90 Synthetic Gear Lube
Product ID: AGL