Tap water is not meant for use in an engines cooling system. Tap water contains many chemicals like chlorine and flouride, and metals like copper and zinc that are found naturally in tap water depending on where you live. These compounds will damage your cooling system. Plus all of these impurities raise the freezing point and lower the boiling point of the water.
Whenever you mix antifreeze with water you must use distilled water. There are not many people that do this practice and it shows by all the radiator failures and water pump failures I see almost everyday.
Distilled water is the only water you can put in your cooling system. They sell it at any large chain supermarket. I use poland spring distilled water, its only $1.50 a gallon with no tax.
As far as mixtures go, 70/30 is really pushing your luck in the summer months. You are lowering your boiling point with that mixture. The only time you need that concentration is if you live up near the arctic circle where temps constantly stay below 0 degrees F. After 80% antifreeze concentration, the mixture's boiling point actually begins to lower dramaticly. A 100% antifreeze concentration will cause your engine to overheat, it's been proven. A 50/50 mixture provides the highest boiling point out of any mixture percentage. Even at 60/40 the boiling point is lower than at 50/50.
|