What is the expected life of a 6039? Mine is 3-4 yrs old and going strong still.

I'm thinking if you change the oil every 3000lbs, keep the right air in the burn chamber, keep 'er clean with a major cleaning/oiling in the spring, it will probably run indefinitely.

Of course there's always a motor or bushing to go out, door gaskets that need to be replaced, things that just wear out like any mechanical device.