I have an '04 625sxc and mine too over heats. Overheating meaning it steamed up and blew out the overflow while in the trails. I did some research and found some stuff called Evans NPGr racing coolant and no more overheating. It's a waterless coolant that's rated to 400 degrees. You simply drain out the old coolant, remove some of the lines to blow the system out to remove ALL the old coolant so the Evans waterless coolant doesn't get contaminated with water. Worked great.