At the beginning of the season before I pulled my machine over I thought I had coolant in one of my cylinders until I found out that the Arctic Cat oil I put in my cylinders in the spring had a slight green tinge to it. Before I figured this out I went asking questions to see what the problem could be if I had coolant in my cylinder. I was basically told to pretty much rule out a blown head seal because Yamaha uses o-rings. The only possibility would be a manufacturers defect and if that was the case the engine woud have blown by now. Everyone I asked told me that they are better and can withstand much more than the traditional head-gasket (This includes my anti-yamaha sources). Is this true? I am also told that the outboard industry is starting to use them. Recently in conversation a friend of mine said that they are not nearly as good as a gasket, but then again he is somewhat of an old-school mechanic and knows nothing about sleds, only four wheelers. Which is true, are o-rings better? I am confused.