I would not use 80/90 weight oil in the transmission as you have a front end loader and the oil is to thick to flow easily. The 80/90 is fine for your front axle but the transmission oil needs to thinner for the front end loader and the 3 point hitch to work properly. YOu can get the right oil at WalMart for a fairly cheaper price then using UDT and it is already properly rated for your tractor. You just have remember that you are living in a area that has extreme temperatures and the thinner oil is required for where you live.