There's practically no limit if you don't mind opening up your wallet and rolling up your sleeves. But you can expect to start spending money after a few thousand hours, and bigger money after 10K.

Age can be just as much an enemy as hours, at least to the rubber and plastic parts. Most of them are not real expensive to replace.

My buddy has a 2001 Deutz 20K unit with only 900 hours, and is having to replace a bunch of minor stuff.

Shrimp