Bought a 172 for flight training about 3 ½ years ago with almost 1800 hours on the Lycoming O320 engine. After a trouble free additional 1700 hours we’re putting an overhauled one in. For a 2000 hour TBO engine I think we got our money’s worth. And there was really nothing wrong with the old one. We’ll have the old one out and new one running in just a few days. Students are waiting