After getting my mower back from 3 weeks of warranty work, it still isn't fixed. They had to replace the head gaskets and carberator. It also had (has) noisy lifters. After running it 10 minutes these lifters are really loud. It will stay that way all day. The only way I can get it to stop is to idle the engine for about 10 minutes. This engine has 107 hours on it. When I got the mower back it still had the noisy lifters. I called my dealer and he said that they called Kohler about the lifters. Kohler told them that the noises were normal and there is no fix. They said under some conditions they may be noisy for 30 minutes. Well mine is constant for hours. I told my dealer that I would try running synthetic oil to see if that would help. He said if Kohler checks the oil they will void the warranty. My dealer admits that Kohler has made a not to par engine. He wants a Kohler rep to check it out this fall. How many users of 25 Kohlers has noisy lifters? I just want to make a case when I call Kohler and start griping to them.