I bought a new 450 Grizzly less than a year ago. We rode it for about 7 months with no issues. One day on a local ride it started smoking. We checked the oil and sure enough it was milky. It had never been sunk or anything like that but we do go through a lot of mud and water. They would not cover it under warranty. I paid to have it professionally rebuilt. The first time we took it back out ( Mudapalooza in Louisiana this May) 30 minutes into the ride it had water in the oil. We had been through water but nothing crazy and every other bike was fine including the 400 Kodiak which is much shorter. I took it back and he redid everything and checked it out. Well this weekend we went back out for the first time and after going through the 2nd hole I made my son stop and check the oil and sure enough, water in the oil. What do we do? The oil is fine riding on dry trails. There is no water in the oil until we go through water.