General Question about Coolant/Antifreeze

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Jeff Strickland - 28 Mar 2008 18:36 GMT

I have a bottle of Zerex antifreeze. It is the DEX-COOL flavor. I bought
this by mistake, but that is not the question.

On the back of the bottle, it lists several makes and year of cars, and the
years of my cars says I need the G-05 flavor, not the DexCool flavor.
Obviously G-05 and DexCool are flavors of ZEREX, and Prestone will have its
own name for the flavors it has. I'm pretty sure you guys won't know the
flavors per se, but why are there flavors?

I don't care about the anti-freeze qualities of coolant because it never
ever gets so cold that freezing coolant is an issue for me, but I do care
about the coolant qualitites, and I suppose my biggest issue is the
corrosive nature of Flavor X and the block/head and Flavor Y.

My question is, what is the purpose of the different formulations (flavors)?
I can look up what the actual formulations are, but why are there different
formulations? Why does the motor care about one over the others (there are
three flavors of ZEREX, Original, G-05, and Dex-Cool, and I assume Prestone
will have more than one flavor as well ...)?

I come from a day when we used water alone, and that was good enough. Then
they gave us coolant. Now there are apparently three flavors of coolant, and
it matters which one I use.

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Bill Putney - 29 Mar 2008 00:24 GMT

> I have a bottle of Zerex antifreeze. It is the DEX-COOL flavor. I bought
> this by mistake, but that is not the question.
[quoted text clipped - 19 lines]
> Then they gave us coolant. Now there are apparently three flavors of
> coolant, and it matters which one I use.

Google "OAT" and "HOAT". This is somewhat of an oversimplification, but
traditional green antifreeze has a relatively high level of silicates in
it. Some early research led manufacturers to believe that silicates
were totally bad in coolant. OAT (Dexron™/Prestone Extended Life™) was
the result. Lo and behold, they found that OAT (Dexcool™) had (still
has) serious problems - that the optimum amount of silicates was less
than traditional green but more than zero (too much created problems,
too little created problems - something about pump seals, cavitation
wear, and corrosion tradeoffs).

Ford and Chrysler worked with Zerex to come up with HOAT/G-05. It does
not have problems.

There are also considerations regarding compatibility of chemicals used
in a given coolant with very specific alloys of copper, aluminum, etc.
The radiator and gasket industries have had to adjust some of their
materials to work well with the more "modern" coolant chemistries. And
to some degree that drives what coolant will work well in a given engine
without causing corrosion, leaking, etc.

I have a theory that Prestones "All Makes All Models" coolant is a close
formulation to HOAT (just different enough to avoid lawsuits, yet having
the essentials) - it is their way of phasing out DexCool (which is a
disaster) while allowing them to save face. I can't imagine them being
stupid enough to repeat the mistake that DexCool was. I have the All
Makes All Models in my wifes Buick as an experiment (please don't tell her).

Download and read this article (there is a "pdf version" button on the
page): http://www.motor.com/article.asp?article_ID=816

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

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