Christopher McCann wrote: > Since water is different everywhere, pH and mineral wise, I can't see how > that argument works. > > Oh yeah, he also said (and we all agreed) that the pH of distilled water is > acidic and that is bad. I argued that with distilled water, you have a known > starting point and can formulate the coolant accordingly. >
I think in most municipal water systems the tap water is slightly basic, to reduce corrosion in pipes. Federal regulations require a range of 6.5 to 8.5, IIRC. Once upon a time, VW blamed hard tap water in the U.S. for head corrosion problems and head gasket leaks on Vanagons, and recommended that only distilled water be used with their special coolant. I have my doubts, though. I tend to think the corrosion was secondary -- the head gaskets would start weeping and this would lead to corrosion of the head sealing surface and a bigger leak.
