Hy-Gard transmission and hydraulic oil is a unique oil developed by John Deere engineers to meet the exact needs of John Deere machines. Hy-Gard fluid is a multi-viscosity fluid with a high-viscosity index. Hy-Gard viscosity places it between ISO 46 and 68 grades. Hy-Gard may be used in many applications specifying either of these grades. The exclusive Hy-Gard formula was designed for use in John Deere equipment. However, it can also be used in many non-John Deere transmission and hydraulic systems.