Cooling system service intervals

[Big Jim]

From high school chemistry. Water is the universal solvent. One of it's prime characteristics is that most anything will disolve in water. At the very least, water will absorbe some of anything that it comes in contact with.

The purer the water, the more it tends to disolve.

Does anyone remember Dowguard? Made by Dow Chemical, it was factory fill in American Motors cars back in the 60's. It was blue in color. It was really nothing more than conventional anti-freeze with blue dye instead of green and pre-diluted with distilled water.

My Escape owner's manual recommends using distilled water when mixing coolant. I'm sure that others may too. I'm also aware that at least some the coolant makers also recommend using distilled water.

My conclusion is that distilled or RO water is desirable for use with the appropriate coolant in automotive cooling systems. Any concern about the distilled or RO water attacking cooling systems is buffered by the anti-freeze, as the anti-freeze was designed to do.

Any real chemists are welcome to chime in.

 

[Kestas]

I've been regularly using DI water from work to make up my coolant for the past 5 years. None of my cars show the horrible stripping of metal ions in the cooling system.

Your chemistry professor is correct, and the above posters are also correct. Pure water can be corrosive to metals. But mixed with antifreeze, as Big Jim says, this action is neutralized.

 

[Quickbeam]

Yes, ultrapure water is "polished" by resin beds. The systems I serviced went like this: prefiltered city water > RO > holding tank > ion resin polished > ultaviolet sterilized > facility. I may have the resin beds and sterilization reversed but that's the way I remember it. Although I only used it for washing I know lots of guys who used it in their cooling systems with no problems but as Kestas points out it was mixed with EG.

 

[Quickbeam]

Ok I checked and I was right. Sterilization occurs after ion exchange because bacterial growth is promoted in the resin bed. DI mixed with EG is no longer DI so either it or distilled will work fine in an engine. Each process leaves different things behind, distilled the ions and DI some solids. It all comes down to your definition of "purity". Wafer fabrication requires both low solids and very high resistivity so DI is used. Think of DI as electrically pure. The reason no metal is used in wafer fab plumbing is because as DI corrodes metal the resisivity goes way down.

Form a solids standpoint it seems distilled would be better but for practical purposes the difference between DI and distilled seems moot once it goes in your engine as long as DI is mixed with glycol. Distilled is cheap and readily availible but I'd use DI in a second if I still had access to it like Kestas does. And as I said it's great to have for washing if you can get past the guilt of "wasting" such large quanities of expensive water.

That's the way I see it. If I'm wrong someone feel free to chime in. I'm surprised this question comes up so much on the internet as there's plenty out there about the two forms of water to read up on.

 

[toocrazy2yoo]

Well, forgetting the water for a second, 15K intervals? How fast are 15K going up on the clock? Jeez, I'm doing 15K every 5 1/2 months! Interval in my owner's guide is 60K, but when I asked the dealer about a 30K service, they want to do the radiator as part of the ($360) 30K package, in spite of the fact the car will be under a year on the road. Of course, I already changed it at 1K because the factory slops were so snotty-slimey.

I think I'm going to go get a bottle of G-05 to have that receipt on hand along with the sparkplug, Cabin Air Filter, Air Filter, oil and filter receipts when I present this thing for 30K service. I don't want em putting whatever passes for factory fill in it. I ran about 6 or 8 gallons of distilled through this thing when I did G05 at 1K, I don't want em slopping it back up again.

They can do their little "inspections", change the serpentine belt, and call it a day. I'll save some money. Knowing the stealers, I'll save probably $50.00.

But 15K, in fleet cars? Sounds like a lot of coolant changing and tampering with the radiators for a 15K interval.

 

[Rico567]

Realizing that dealers are in the business of selling service, mine was still at a loss for words when I asked their service guy why they wanted to fill/flush my cooling system (for $180!!!) at 30K when the coolant in the system is rated by the manufacturer at 5yr/60K. When I asked the service manager "Are you telling me that this rating is invalid in your car?" he was pretty much stuck, because he evidently was acute enough to realize that if he said "Yes." then my next question was going to be "Why?" The Kickapoo Joy Juice I'm talkin' about in this case is "the orange stuff."