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