which is best? just using plain distilled water or distilled water "plus" an original MB coolant with anti-freeze? they say that using coolants has pros and cons. some say that when you use coolants, the tendency is that, it can solidify in the radiator and cause some sort of blockage hence diminishing water flow thereby increasing the working engine temp. however coolants were designed to protect the radiator from rusts and corrosion. Some people say, "just use distilled water and you're good to go". the only downside in using plain distilled water is that the radiator easily heats up and even reaches a hundred degrees C. which is which guys?