I have 160 hrs. on a Kohler 28 EFI that I purchase in May. It is on a Lazer Z. After the initial oil change I noticed that I was using oil about every 10 hrs. No smoke and the engine runs great. My Exmark dealer told me to keep track of the amount that I am using so that she can inform Kohler. I put approximately 3 oz. of oil every 15 hrs of use. She called Kohler with that figure and Kohler said that 1 oz per hour of use is acceptable. I cannot believe this. I have a 26EFI that doesnt use a drop. Guess I've bought my last Kohler engine.