John Deere hydraulic oil is used in transmissions and hydraulic systems in John Deere and other brands of tractors. According to the John Deere website, it is recommended for equipment with either common system reservoirs or separate transmission and hydraulic systems, including those with wet brakes and wet clutches.
John Deere's hydraulic oils are marketed under the Hy-Gard name. Hy-Gard and Hy-Gard low-viscosity hydraulic transmission oils provide the best performance and wear protection for John Deere hydraulic and transmission systems, according the John Deere website. Hy-Gard exceeds J20C specifications, while Hy-Gard low-viscosity is for applications calling for JDM J20D. John Deere Bio Hy-Gard II is a biodegradable hydraulic oil alternative that is touted as being safe to the environment.
Hy-Gard is service rated for a wide range of tractors and equipment to use in place of original equipment hydraulic oils by Ford, Massey Ferguson, White, Kubota and Caterpillar, among others. Hy-Gard oil can be used in most applications calling for 10W-30 or 5W-30 engine oil for transmission and hydraulic oils, according to the manufacturer.
The manufacturer claims that Hy-Gard oils include a viscosity improver additive that insures correct viscosity in a range of operating temperatures. The viscosity is between the ISO grades of 46 and 68 @ 40 degrees Celsius, according to John Deere specifications.