As a professional mechanic, I know that ALL parts are susceptible to failure at some point, but I also believe that these same parts can last a very long depending on how you use them. If you allow any machine / engine to warm up, it will easily last much longer than another one that is not warmed up prior to use. Most mechanical things of this type fall into type of scenario. Now take into consideration of the preventative (not just the repair / breakdown) maintenance it has gotten over its life span. That will tell you how it was "LOVED" versus used to pile up / move dirt. I pay less attention to the hour meter & year of manufacture compared to how the machine actually runs. In all honesty, the age & hour meter reading help to the buyer manage a lower purchase price AND it helps determine when to service it. Your question really centers around an unanswerable riddle! For example, when do you replace the water pump, thermostat or fan clutch or a truck? These parts are all known to fail at some point, but who changes them before the fail? Then, ask yourself, who changes them prematurely in order to avoid those type of related failures or possibly larger repair bills?? Your question is actually a very, very good one, but it is also one that is not easily answered. I will caution you to only buy a machine that you feel comfortable with owning. Try to remember that pretty machines don't make anymore money than a ugly one. To me, the mechanical condition is everything to me; cosmetics are simply a bonus!! As soon as you buy one, perform a complete service on it; change ALL of the filters & fluids before pressing it into hard / everyday service! Good luck on your selection!!