Proper coolant as opposed to plain water not only lowers the temp. that the coolant will freeze but also raises the temp at which coolant will boil. 212 degress Farenheit at sea level, less higher up. You can easly have your straight water turn to a vapor and have major problems. Vmax runs about 205 normaly I believe. All water wetter does is help transfer heat from metal to coolant. Read labels guys all the info is there. Coolant is always recomended 50/50 with water unless premixed. Then it gets more complex with aluminum engines and electrolysis. Plain water in a aluminum water pump will cause a charge and remove material from places you don't want it removed from. Not overnight but over time.