Questions and Answers

More On Anti-Freeze And Water Q. Hello Vince: I just noticed and read your article on anti-freeze. I also noted the comments from the gentleman from Base. Your comments on hard water reactivity hit home as I noticed and experimented with a process that seemed to solve the problem. When I was in the business I noticed the following.

Cooling systems that were untouched, that came to me for the regular 5 year overhaul were usually quite clean. Cooling systems that had been regularly flushed were a different story. So, I began a process of using only demineralized water in cooling system and instructed my customers to do the same. This made a tremendous difference in the cleanliness of the overall system.

Why is it not recommended that only demineralized water be used in cooling systems? Would this not solve the problem of hard water reactivity?

Best of luck.
Frank

A. Well, back in the old days it was always stated to use distilled water in cooling systems and batteries. Difficult to do but as long as the city water was a fairly good quality and reasonably soft, it was almost as good.

In the 2003 service manuals I was hard pressed to find any specific recommendations. GM says "50/50 mixture of clean, drinkable water and use only GM Goodwrench DEX-COOL or Havoline DEX-COOL Coolant."

Honda Says "Always use Honda All Season Antifreeze/Coolant Type 2 (P/N OL999-9001). Using a non-Honda coolant can result in corrosion, causing the cooling system to malfunction or fail. Honda All Season Antifreeze/Coolant Type 2 is a mixture of 50% antifreeze and 50% water . Do not add water." That sounds like the best way to control quality of the water used in the mix.

Nissan says "Use genuine Nissan anti-freeze coolant or equivalent mixed with distilled or demineralized water."

Toyota agrees with Nissan "The coolant should be mixed with plain water, preferably demineralized water or distilled water."

I couldn't find any specific recommendations for Ford and Chrysler.

I always try to use distilled or demineralized water in the cooling systems I service, In a pinch the city has water of sufficent quality to use as well. I have this big A/C unit on my roof and I have the drain tube going into a couple of 55 gallon drums. Viola! Instant distilled water. During the winte I buy demineralized water from a local water supply company.

As an aside for battery fills, I use a 50/50 mix of battery acid and distilled water in my battery fillers.