I have a Kohler 26 HP Twin on a ZTS 7500 zero turn mower that has 2330 hrs. of running time on it. It is all original except the carb. & starter. Uses a little oil but runs well. The trans still going but a makes a noise starting out. I don't mow with it any longer so I took belly off & tow a small trailer to do a lot of odd jobs. It is used every day & not unusual to run 5 or 6 hrs a day. It's about 10 yrs old. The Kohler tech boys were impressed that an air cooled eng. ran that many hrs. & still running. I am going for 3000 hrs. Shows what good maintenance will do.