John Deere recommends that you put Low Viscosity Hy-Gard or Hy-Gard Transmission oil in their Hydro or Gear Transmissions. The Low-Vis is used for factory fill in the Hydro and Hy-Gard in the Gear Transmission.
Hy - Gard
Turf-Gard Low viscosity HY-gard (J20D)
Mobilfluid 424
any hydraulic transmission oil such as Hy-tran Case IH or Hy-Gard John Deere
10w40 for the engine and hy-gard for the transmission.
John Deere recomends using JD Low viscosity Hy-Gard Transmission/Hydraulic fluid in it's equipment. Please check your owner's manual for any specific requirements, if one is available. There is no equivalent on the market that I could find. The fluid keeps solvent in low temperatures and can be used in Transmissions and Hydraulics, separate or common resevoirs. I am not a John Deere expert..just a owner/user. From a web site... Hy-GARD® JDM J20C Transmission and Hydraulic Oil John Deere Hy-GARD® provides the absolute best performance and wear protection for John Deere hydraulic and transmission systems. John Deere Hy-GARD® 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 Hy-GARD® is an exclusive formulation containing a viscosity improver additive to assure optimum viscosity at all temperatures. This additive provides critical component protection, especially during startup and under heavy load. John Deere Hy-GARD® also contains friction modifiers to provide smoother clutch engagement and higher braking capacity with minimum chatter. John Deere Hy-GARD® exceeds JDM J20C specifications and only John Deere Hy-GARD meets John Deere's exacting performance requirements.
low viscosity Hy-Gard Transmission and Hydraulic Oil
John deere hy-gard or any good trans. Hydraulic oil
Transmission Oil Low Viscosity HY-GARD® (JDM J20D)
Although I can't say for certain, it may take Hy-Gard.
DTE 15m is a ISO Viscosity Grade 46. A comparable Deere oil would be Bio Hy-Gard 5W-30.