This might be interesting. I replaced the coolant (had lost some in the pas
pump replacement period, as one time the thrown belt took out the electric
fan pump switch) in my 1976 XJ-S.
The coolant I bought was designed to be mixed with water. It was made by
Castrol which in Australia is I believe fairly well regarded. It wasn’t
The bottle said, “Mix with DEMINERALISED or SOFT water.”
I thought this was interesting because I know there was a bit of hoohah
(gotta love that word, although I also like “brouhaha”) about someone’s home
demineraliser, and the suggestion that, “if it’s a water softener, it’s
worse than tap water” or some such.
I don’t want to fan any flames, but according to Castrol, soft water is no
worse for this purpose than demineralised water.
Well, I was intrigued.