Startup is the biggest killer, followed by the cold running time that it takes to get things warmed up. Once it's warm the wear and tear is minimal. I've seen 6,500 hours on Kubota diesels on construction equipment before. then again, we've found that the Kubota engines are some of the toughest things around as long as they are properly maintained. Most of ours fail by 4,000 hours though. Then again, that's because there's more short term running involved on them instead of 24/7 operation. At 6,500 hours it may indeed run a fair time longer but I would also consider that it may develop issues in the near future and budget accordingly. Many times I've seen that a change in ownership brings a sudden change in performance due to the different styles of handling between the new and previous owner so you never know.
Mark & Leann Quasius
2016 Cornerstone 45A
2007 Allegro Bus 42QRP (Sold)
2012 Jeep Wrangler Unlimited - Rubicon