Why do you people run distilled water on cooling system and flush it, is it neccesary?

When you drain the cooling system on a car it doesn't completely empty it, you'll only get is 40-60% out depending on the car. This means part of the water you put into the radiator for the flush will stay in the cooling system, if you use tap water and flush it then 40%-60% of your radiator will be filled with it after the last drain, and as you want a 50/50 mix that basically means all of the water in the system will be tap water, with all the minerals and impurities which are bad for your car. Using distilled means that after the last drain you'll have distilled only in your radiator.

Distilled water has vinegar.. Vinegar breaks down crystals rust scale and so on- yes... Its very important to flush a radiator every once in awhile- kits are sold at auto parts stores as well as better flushing chemicals and agents for this purpose including one that you hook to a water hose to remove all trace of the distilled water and any deposits which also stay behind. If they remain in the cooling system and are LOOSENED by your flushing component they can do more harm clogging waterways than if they were never messed with to begin with. The waterhose method is the best way- running the waterhose pressured water through the system for 5-10min. If you can unbuckle the lower radiator hose is added extra benefit to ensure bigger pieces of contaminants are rid of. Personally I wouldn't advise driving it while the flushing agent is working- you could get stranded somewhere if an afore-mentioned bigger piece of contaminant clogs something. Idling it in park is just as good- so long as you keep an eye on your temp gauge. The better the flushing agent the cleaner and more efficient your cooling system will be.

Distilled water pH is acidic, tap water is generally neutral and some water is more alkaline. The more minerals the more alkaline the less mineral the more acidic. Distilled or demineralised water does not contain any vinegar.

Using distilled water is a garage mechanic tale in trying to use "pure" water that won't create deposits (if you regularly flush your system deposits are not an issue). However, distilled water is actually bad - when water is distilled, or “stripped,” of its minerals and impurities, the resulting solution is composed of chemically imbalanced “ions.” This leaves distilled water “ionically hungry,” so it will actually strip electrons from the metals in a cooling system as it attempts to chemically re-balance itself. As it chemically removes electrons from the metals of cooling system components, distilled water eventually does extreme damage that could lead to cooling system failure. Chemically speaking, this explanation is spot on, but it isn't from me, it's from the engineers at Hy-per Lube. https://www.hyperlube.com/blog/blog/why-you-should-never-use-distilled-water-in-your-cooling-system/

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