I use the Canadian Tire 15W40 in all my non JD tractors and the pickup for over a year now. No problem whatsoever with the oil. A CT pail is $30 while the JD goes for $60 and over. We still use the JD oil in our JD's. Religious thing I guess. I change my oil every 100 hours. Not sure if the CT oil will last if you change every 250 or 500. It might, I just never tried it. I also use the Gear Oil from CT. Don't think there is any difference between it and the JD GL5. The gear oil is used in a heavy duty roto tiller transmission and gear box with a 4WD tractor in front of it. It has lasted well. Why Spend the extra money? I think JD is getting rich off the oil.

We have used other brand Hydraulic fluid in our JD's once and it dissolved the break pads which caused a whole series of problems later on. If I were you I would stick with the Hygard if you run JD.