OK, Yeah, I thought it was better than that and that you had bought it. So I wrote a long post this morning about what to do once you have it.
Obviously I was jumping the gun.
Yes, I'd run away from that 580 and think twice about going back except maybe to thank the guy for being such an *AH* salesman. Being generous, there's just the slightest chance that me might be trying to save you from yourself in the only way he knows. Sounds like it worked.....which is good. I'd say something far more than the leak is wrong with that deal.
It's not impossible at that many hours, but unlikely. I've bought JD310s with 6/7000 hours which worked just fine although they eventually needed about 5K in just old age maintenance = pins, bushings, hoses, tires, batts. But basically nothing really wrong. So maybe such a thing exists at 8500 hrs ?? I doubt it. But if everything seemed to work I'd offer 12. BTW, I'd be looking for another dealer myself. My own experience is that I've rarely bought anything worth keeping from a dealer.
IN THE WORLD OF OLDER TRACTORS, "KEEPERS" TEND TO COME FROM PRIVATE INDIVIDUALS, NOT DEALERS.
A Private Individual Owner is just what you are going to be. Would you trust buying from yourself?
Look, buying a commercial duty machine has little in common with buying a compact tractor. And this is a compact forum. If you are going to keep looking at 580s and 310s, I wonder if you need to back up, and find a dealer who sells these yellow machines exclusively. Maybe go to your local commercial JD310 shop - ask any operator at any construction site for a recommended shop. Snoop around and try to buy lunch for a salesman you get along with. I'll bet you that every saleman there has a private list of private owners that he has known for decades. Mine sure does.
Luck, rScotty