How many hours can you expect one of these engines to give good servise. I bought a used 03 with 1100hrs on it in march to mow my 5 acre yard. It runs great and uses no oil in the 40hrs I put on it so far. I wanted a new one, but didn't have the cash. I gave $3300 and hope it will give me a few years before it needs replacing. Thanks for any advise!