And I agree. With all the facts that are out there, the bottom line comes to, how well you maintain your cooling system. Yes what I was reading in other replies was so much about air in the system. And my point is air is a part of water which is require in the coolant system. While I have a shop and work on theses cars every day I don't always understand all the agruments on the subject. But I can say without a doubt, a properly maintain cooling system will bless you with less problems. I am sure iron in water varys from town to town. Other elements in the water will vary too. But everyone can maintain there cooling systems and prevent problems just the same way you would change your oil. It is not that I am trying to be smart,I just think people forgot what the first question was all about and got off topic kinda.