I don't care what some say... distilled water DOES NOT prevent corrosion!.
The reason distilled water is used on cooling systems is the minerals and ions typically found in tap water can be corrosive to internal engine components, and can cause a more rapid depletion of the anti-corrosion additives found in most antifreeze formulations. Ofcourse there are benefits of using distilled water and its what I use to dilute my coolant.
But some have assumed the suggestion of using distilled water in cooling systems as it having some kind of rust prevention.
FLASE.
Water even at its most purest form contains oxygen. I would assume same rust will result on IRON from normal tap or distilled water if system was filled and left alone for a time, Unless you tap water has a high level of contaminants. Tap water might affect other non IRON metals, where distilled might not, but I don't consider that type of corrosion as rust. If your cooling system has any type of metal that may corrode in water, it will still corrode in tap or distilled water would be my main point.
------------------------------------- So now that my non-professional rant is over
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SO.... Back to HERE we are talking about storing a system either empty of filled with distilled water... AND NOT RUNNIG IT!
So your concern should be rust/corrosion and not really coolant contamination.
I would dare say an empty DRY system should corrode less than a WET water filled system, and I'm thinking more of the IRON block than any other metals.
A recent example: A friend recently told me he uses nothing but distilled water in his cooling system, because he read that is prevents rust. LOL
This is the type of argument Im trying to target.
I'm not an expert, far from it and I could be wrong
