Californua resident where freezing is not an issue, I have always used distilled or deionized water in my cooling systems. Mainly because of cleanup disasters when losing a hose or water pump. Many race tracks ban antifreeze for this reason.

Also no environmental issues to deal with when changing coolant.

Have always added either a Prestone type anti-rust or a Water Wetter type product which includes anti corrosion substances.

I am aware of higher boiling point attributed to antifreeze mixtures,,,however with a 15 pound radiator cap, the addition of antifreeze offers marginal benefit. Perhaps 12 degrees.

One question I have always had was,,,must I continue to drain water and replenish occasionally,,,or can one just throw another can of anti-rust from time to time,,,within reason of course.

Some friends think I am nuts,,,,however my 71 Corvette is almost 50,,,original radiator and heater and coolant shows no rust.

I am now wondering if I should have same behavior on my aluminum headed Challenger. Runs a aluminum radiator with a 190 thermostat.

Opinions??

Anyone else doing this?

I've been using distilled water for decades, whether with anti-freeze or not. I add Water Wetter, whether anti-freeze or not.
Seems to me the lack of minerals is a good thing for cooling systems, and my radiators that are 30+ years old and still in excellent internal condition seem to back that up.
Out of curiosity one year I put a sacrificial anode in one radiator and it showed almost no corrosion.
I change the water in the racecar out every couple of years, the coolant mix in the other vehicles maybe every 5 years, never seen anything to worry about.

there was a thread way back & I dont remember if they said distilled or ionized water was better or if they worked the same (in this app) or if it was splitting hairs. I would say some antirust/water pump lube is needed no matter what & yes on the sacrifical anode if useing an alum rad

I wonder what either straight Evaporust Thermocure or diluted with distilled water Evaporust would do as a long term coolant?

Evaporust is neutral 7 ph and mostly water.

I have read here on Moparts about people temporarily using the original Evaporust to clean the insides of the cooling system with good outcomes. Thermocure is their newer specialized product.

https://evapo-rust.com/thermocure/

https://evapo-rust.com/wp-content/uploads/2018/08/Thermocure-Safety-Data-Sheet-2018.pdf

Some good discussion about Distilled Water
http://speedtalk.com/forum/viewtopic.php?f=1&t=11055

Discussion anyway, not so sure about the good part.

Well, from an anti-freeze scientist's perspective.....
1. Distilled & de-ionized both remove the ions, which is what you want to do. Distilled is 100% pure water & de-ionized is 99.9% pure water (no ions, some dirt)
2. You do need to run some type of anti-corrosion product (e.g. water wetter type stuff)
3. Water Wetter has very poor aluminum protection (I've tested it personally). Works just fine for iron heads/block
4. For aluminum heads, I suggest either Royal Purple or Lucas (formulas are identical except for color - I've analyzed both myself)

Hope This Helps!

^^^ Good info

While distilled water is plentiful,where does one source deionized water?

https://chemistry.stackexchange.com/questions/7467/is-pure-water-very-corrosive

You could struggle through this one and decide. I'm not a chemist by any means but I think I'll stick with WallyWorld distilled water and SuperTech antifreeze. What you gonna' use instead? Stuff from your local water company or well? I don't know where you could find de-ionized water. 50 years ago you colud go to the fuel branch on any SAC base and they'd have it. As I recall, it was used in water injection for takeoff of the B-52s and KC-135s J-57 engines.

Per PurpleBeeper, distilled IS deionized,
$0.99 per gallon at a drugstore, KISS. LOL

Joe

No, deionized water is not distilled water or vice versa.

Just used distilled it's easy and cheap to find.

https://en.wikipedia.org/wiki/Purified_water

I've worked with virtually every purification method used for power boiler feedwater make-up including EDR, RO MF, ion exchange, and distillation. Sniper's reference is accurate.

I have used one of these units for 10 years or maybe more. Great for rinsing windows of home after washing, thereby eliminating need to squeegee,,,rinsing vehicles after washing, eliminating chamois drying,,,,etc. great for filling vehicle cooling system.

It creates deionized water, from your garden hose. That is how it works to eliminate water spotting.

https://crspotless.com/

You cant drink DI water, it can kill you, you can drink distilled water...
oh and antifreeze is good for keeping the Ferrel cat population down!

Ok, gentlemen.....distilled water has been boiled, turned into stream & cooled off (condensed) so it's 100% pure water. It will NOT kill you, but it will suck a few vitamins out of your body when you drink it. The same is true for de-ionized water, but with deionized water, regular tap water is pumped through "ion exchange resin" like someone else posted.....basically, you're removing "salts". RO (aka reverse osmosis) water is regular tap water run through an ULTRA fine "screen", so to speak. The holes are as small as some atoms....SMALL holes, so RO water will work too (ions/salts removed). You can use any of these waters for coolant.

Well water is normally the worst, tap water the second worst & distilled/DI/RO water are all fine. You can buy de-ionized (DI) water in grocery stores too and I use it if some place doesn't carry distilled water...no problem. Those little things you screw onto your faucet or the water pitchers with the filters in therm are making de-ionized water, but I've never tested to see exactly "how de-ionized" the water is after filtering. I just buy gallons for a dollar and don't worry about it.

Key into amazon,,,water tester,,, will bring up 15 dollar electronic water testers that give water purity. Have used one for years to test water purity. Cannot forward url of product page, since now using amazon app instead of keying amazon into address bar,,,,copy and paste of url no longer works for me.