dan, not to be rude or disrespectful but your insistence that you have "knowledge about cars" runs entirely contradictory to a lot of the statements you make. let's remember some hits such as: "i don't use a torque wrench" and "avanti's are muscle cars" from your seminal album "DTM summer jams and talkin' nonsense".
at any rate, using distilled water in cooling systems has long been common practice. i skew younger among my colleagues and all those old heads even hammer about the use of distilled, have for years and, that's all i heard growing up from any car guys i knew.
go look at any car repair manual printed in the last 40 years-- chilton, haynes, etx. and they all will mention distilled water. every.single.one. so to say you didn't know is ignorance at best; but more like lazy and stupid.