Demineralized Water


Old 01-08-07, 01:48 PM
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Join Date: Apr 2005
Location: Philadelphia
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Demineralized Water

Can I be confident that when a dealer gives my vehicle a reverse flush of the cooling system, the service mechanic will add demineralize water to the antifreeze instead of tap water? Has anyone caught them using tap water?
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Old 01-08-07, 09:54 PM
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It depends on the dealership.
I would not be confident about this.
Why not just ask.
Old 01-09-07, 05:09 AM
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I just checked my maintenance manual and it appears I need not be concerned about this until my vehicle has 100,000 miles before replacement is due. But it needs to be checked after every 15,000 miles to be sure that I am protected. Its been about over 18 years since I purchased a new vehicle and back in the old days, the recommendation was to change it every three years I believe. The vehicle is a Toyota 4Runner. However, I will wait and see if others have an opinion on this.
Old 01-09-07, 06:16 AM
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I confess in all the years I've owned cars and trucks (many of them Toyotos), I have NEVER used demineralized water in the cooling system.
Old 01-09-07, 06:37 AM
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Calcium is a mild poison to cooling systems. Plus there are other hard minerals in tap water that can wreak havoc with cooling system chemistry. I too have used tap water in the past. But it's better to use demineralized or distilled water to make up coolant. I have it available to me on tap at work, so it's a no-brainer to me.
Old 01-09-07, 08:59 AM
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Thanks all,
The two new vehicles that preceded my present purchase had some type of buildup on the interior radiator fins that occured after using tap water and I don't want this to happen four years down the line like it did before.
Old 01-09-07, 09:04 AM
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Ask. If they use tap water, bring 2 jugs of distilled water with you and ask them to use that instead. You could also just do this yourself, it's a pretty straight forward job.

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