Amsoil Authorized Dealers John & Zenaida Cardell

Hydrostatic 20W-50 (AHF)

Amsoil Hydrostatic Transmission Fluid 20W-50 (AHF)

Product Highlights View Full Description

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.

It 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.

Package Sizes (AHF)

AHFQT (AHFQT-EA)1-Quart BottleEach
AHFQT (AHFQT-CA)1-Quart BottleCase of 12
AHF1G (AHF1G-EA)1-GallonEach
AHF1G (AHF1G-CA)1-GallonCase of 4
AHF05 (AHF05-EA)5-Gallon PailEach
AHF55 (AHF55-EA)55-Gallon DrumEach

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 230ºF, 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


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* and Cub Cadet*. Not for use in engines.


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.

Service Life

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

Amsoil Hydrostatic Transmission Fluid 20W-50 (AHF)
Viscosity Index (ASTM D2270)137
Kinematic Viscosity @ 100˚C, cSt (ASTM D445)19.4
Kinematic Viscosity @ 40˚C, cSt (ASTM D445)162.4
Viscosity Index (ASTM D2270)137
Pour Point ˚C (˚F) (ASTM D97)-37 (-35)
Fire Point ˚C (˚F) (ASTM D97)264 (507)
Flash Point ˚C (˚F) (ASTM D92)250 (482)
Four-Ball Wear Test (ASTM D4172 @ 40 kg, 75˚C, 1200 rpm, 1hr), Scar, mm0.35
Viscosity CCS, cP @ ˚C (ASTM D5293)4270 (-30)

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