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20W-50 Synthetic Hydrostatic Transmission Fluid (AHF)

 20W-50 Synthetic Hydrostatic Transmission Fluid (AHF)
Product Code: AHF • Brand: AMSOIL

AMSOIL 20W-50 Synthetic Hydrostatic Transmission Fluid is specifically formulated to deliver smooth, responsive operation in zero-turn mowers, stand-on mowers and other equipment professionals rely on to make a living. AMSOIL 20W-50 Synthetic Hydrostatic Transmission Fluid is a high-zinc formulation that fights wear and helps preserve mower speed and responsiveness.

Package sizes include:

1-Quart Bottle
1-Gallon Bottle
5-Gallon Pail
55-Gallon Drum

See Pricing or Place an Order
MSDS Data Sheet

Product Details

Product Applications

Use in hydrostatic transmissions that require 15W-50 or 20W-50 oil recommended for: API SM, SL, SJ, SH or SG, including (not limited to) those found in zero-turn, riding and stand-on mowers made by:

  • SCAG*
  • Toro*
  • Ferris*
  • Snapper Pro*
  • Gravely*
  • Ariens*
  • Exmark*
  • Walker*
  • Hustler*
  • Wright*
  • Dixie Chopper*
  • John Deere*
  • Husqvarna*
  • EverRide*
  • Bad Boy*
  • Cub Cadet*
Note: Not for use in engines.

*All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use. All products advertised here are developed by AMSOIL for use in the applications shown.

Product Description

AMSOIL 20W-50 Synthetic Hydrostatic Transmission Fluid fights wear and viscosity loss during continuous, severe-service operation, maximizing mower speed and operability. Unlike motor oils, Synthetic Hydrostatic Transmission Fluid is purpose-built to withstand the unique demands of hydrostatic transmissions. It lasts up to 2X original equipment manufacturer (OEM) recommendations, helping professionals save money and reduce downtime.

Maximizes Mower Speed & Responsiveness

In many zero-turn mowers, oil pressure drives the wheel motors. Fluid that fails to protect against wear can cause the tight tolerances in the wheel motors to widen, which reduces oil pressure and erodes speed and responsiveness. Fluid that thins at high temperatures can have the same effect. AMSOIL Synthetic Hydrostatic Transmission Fluid contains high levels of zinc-based anti-wear additives to help maintain those tight tolerances, while its synthetic base oils naturally resist viscosity loss in extreme heat. As a result, it helps maintain mower speed and responsiveness for increased productivity.

Commercial-Grade Wear Protection

Transmission fluid must form a thick, durable film on gear teeth and other components to guard against metal-to-metal contact and wear. The mechanical action of meshing gear teeth, however, can tear apart or shear the molecular structure of the fluid, leading to viscosity loss. High heat can also cause the fluid to thin. The thinner fluid can fail to protect against wear, reducing mower life and increasing maintenance costs. AMSOIL Synthetic Hydrostatic Transmission Fluid's naturally tough synthetic base oils resist viscosity loss due to shear and high heat, promoting the formation of a durable sacrificial anti-wear film on components that helps extend mower life.

Maintains Cleanliness

High ambient temperatures, combined with hydrostatic transmission temperatures that can exceed 230°F, cause some conventional fluids to break down and form harmful deposits. AMSOIL Synthetic Hydrostatic Transmission Fluid features naturally heat-resistant synthetic base oils, which reduce deposits and help keep equipment clean and running properly season after season.

• Fights wear for smooth, responsive operation
• Purpose-built to outperform motor oils
• Resists high heat and shear


AMSOIL 20W-50 Synthetic Hydrostatic Transmission Fluid is compatible with other synthetic and conventional motor oils and transmission fluids. Mixing AMSOIL oils with other oils, however, will shorten the oil's life expectancy and reduce its performance benefits.

Aftermarket oil additives are not recommended for use with AMSOIL transmission fluids.


AMSOIL 20W-50 Synthetic Hydrostatic Transmission Fluid is recommended for 2x original equipment manufacturer (OEM) recommendations.


This product is not expected to cause health concerns when used for the intended application and according to the recommendations in the Material Safety Data Sheet (MSDS).

Click here to view the MSDS Data Sheet for AMSOIL AHF.

Keep out of the reach of children. Don't pollute. Return used oil to collection centers.

Technical Data

AMSOIL 20W-50 Synthetic Hydrostatic Transmission Fluid
Kinematic Viscosity @ 100°C, cSt (ASTM D 445)19.4
Kinematic Viscosity @ 40°C, cSt (ASTM D 445)162.4
Viscosity Index (ASTM D 2270)137
Pour Point °C (°F) (ASTM D 97)-39 (-38)
Flash Point °C (°F) (ASTM D 92)260 (500)
Fire Point °C (°F) (ASTMD92)270 (518)
Four-Ball Wear Test (ASTM D4172B @ 40kg, 75°C, 1200rpm, 1hr), Scar, mm0.35
CCS Viscosity, cP (ASTM D5293)6895 (-15)

 20W-50 Synthetic Hydrostatic Transmission Fluid (AHF)

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