It is very important NOT to use tap water from areas with high mineral content in a cooling system. I recently gave my little brother an AMC (Michigan/Ohio lineage) with a radiator TOTALLY stopped up from mineral deposits. Water pump in one of my Lincolns came stopped up everywhere except impeller blades. These calcified deposits are rock hard. No elixer can get rid of them. Your only choice is to replace the affected components. Bill Robertson #5939 >--- In dmcnews@xxxxxxxxxxxxxxx, "David Teitelbaum" <jtrealty@xxxx> wrote: > > It is cheaper to just remove the old stuff (dispose of properly, not > down the sink!) flush the system with soft water, and then refill with > 50/50 soft water and a premium brand of anti-freeze. Don't forget to > bleed all the air out.