Re: How many hours are too many?
I do fluids, filters, and grease my x485 once a year, but I only put about 50 hrs on every year. I bought it in June 2015 with 240 hrs and I just passed 440 hrs last week, almost exactly 4 yrs after the purchase.
To me a used machine doesn't scare me much but I prefer spending a little more for something I am sure is going to last, and use that approach on cars as well. I tend to find something a bit older but with fewer miles/hrs on it than it should. It indicates lighter use and better care. My 2006 Silverado had 96,000 miles on it when I bought it 3 years ago when it was 11 years old. That's less than 9,000 miles a year. Same with the x485, it was 12+ years old and only had about 20 hrs a year put on it.
I haven't been afraid of high hour JDs in the past but at my stage in life now (young kids) I don't have the wrench time like I used to. If I had time high hours is fine as long as the seller took care of it from what I can tell. Never had terrible luck. It does increase the chance of failures happening though. 1,500 hrs later on an air cooled gas engine and you just have things with wear on them, no matter how well taken care of.
Also, many here have no problem with 2,000 hr diesels, and while the engine may be fine and only be through 50% of its effective life, I worry about the rest of the machine. The deck may have a lot of wear and other parts could have seen a lot of degradation over 2,000 hours. Outside of the engine much of the same parts are used on the diesel models as the gas models, so it's not like the dash cluster, frame, and all types of other parts won't go bad. If a lot of those parts go bad on gas models by 1,000 hrs they will on a diesel at 1,000 hrs as well.
JD 2003 X485, JD 54" hydraulic 4-way blade, JD 647 rotary tiller, 2x 50 lb wheel weights, 62" Edge deck.