Has any one ever thought about or used de-mineralized water in the 50/50 mix of coolant. I work on a major radar system and we use water thats filtered to 0.06 parts per million and it has great heat dissapation characteristics. How well does it effect performance, if it brings down the temp at all.

 

I'm not a scientist, but I thought that distilled water was demineralized as well as deionized. When adding water I always put in the distilled and when I flushed my radiator on my old truck I used a 50/50 mix and didnt notice a difference. But the thermostat would still open at that temp so it would stay at the same temp in theory.

 

I think that the major benefit of demineralized or distilled water is corrosion prevention...

 

It won't make a noticable difference. The reason for using distilled water is to prevent deposits of minerals from clogging things up. This is more neccesary on smaller high performance engines with close tolerances in the cooling system (like motorcycles). For cars and trucks tap water or filtered is fine.

 

Especially with Dex-cool distilled water should always be used for mixing. Dex-cool is extremely sensitive to minerals. Contaminants in the water can cause it to turn to a sludgy gel. "Distilled" is the same as "de-mineralized".