Originally Posted by milhan

If you put straight water in without antifreeze, it will boil over, and it will freeze if it sits in temps below freezing. coolant has a higher boiling point and a lower freezing point. Im not sure about the race car thing, but it sounds a little fishy. Its true you will get better heat transfer with straight water, but your cars engine gets hotter than 212 degrees Faherenheit which is the boiling point of water at atmospheric pressure at sea level. In the mountains the boiling point changes because the air pressure is differant.