So let's get straight to the point. Sled kept overheating to about 210 degrees. Tried limping it out the woods as I was alone. Brought to dealer and they replaced my thermostat as it was stuck. Now I noticed my coolant is darker green color but the dealer said it was fine. I believe it is not fine and I found black residue in it. Almost smells burnt. Could this be an o ring failure? Is exhaust getting into my coolant? Should I flush it or just ride it and wait til something happens.. still have 2 years of warranty left..