Engine 721D Transmission Oil

Hey all, buddy of mine gave me 5 gallons of Super Trac 303 hydraulic oil. I'm about due for a transmission oil change and was wondering if this is ok to use in my 721D Grasshopper. I did notice its medium grade while the Mobil DTE 26 the owner's manual recommends is a heavy medium. MSDS states the Super Trac has a lower viscosity.. thanks for any advice

I may be wrong, but I think there is a big difference between hydraulic oil and tranie oil. I would check with your local petroleum distributor to see if the Super Trac and the Mobil are compatible. I would not do this without a ton of investigation.