The more I think about this, the more I think it may be normal for the First axle change. I would be more concerned if it was not the first oil change. When I mentioned it to the dealer, he didn't seem to think it was unusual. Also, Are you sure the front axle had UDT2? Both dealers I talked with stated it is 80-90 in the axle. I even told one that I was going to change the front axle with UDT2, and he said "I wouldn't do that. It comes with 80-90. My axle oil is also black like that. I am at 275 hours. I will take another look at it when I reach 400 hrs. I am inclined to believe that because of the cost of UDT2, the manufacture has a good reason to use 80-90 in all tractors out the door. Best Wishes. Larry