Anti-freeze, glycol vs. DexCool

I never really noticed a consensus here, so figured it would be worth asking.
Our '94 Acclaim 3.0L came to us last year with DexCool in it (pink). The
factory shop manual says to use glycol, then adds all sorts of stipulations to that, such as:
"50/50 Glycol and Water (.82 btu) is the recommended combination... The radiator, water pump, engine water jacket, radiator pressure cap, thermostat, temperature gauge, sending unit and heater are all designed for 50/50 glycol. "Where required, a 56 percent glycol and 44 percent water mixture will provide a freeze point of -59C (-50F). "CAUTION: Richer mixtures cannot be measured with field equipment which can lead to problems associated with 100 percent glycol." (this last is all in boldface, and it makes absolutely no sense to me)
"The use of aluminum cylinder heads, intake manifolds, and water pumps requires special corrosion protection. Mopar Antifreeze, Prestone II, Peak or antifreeze containing Alugard 340-2, or their equivalent are recommended for best engine cooling without corrosion. When mixed only to a freeze point of -37C (-35F) to -59C (-50F). [sic] If it looses [sic] color or becomes contaminated, drain, flush, and replace with fresh properly mixed solution."
"Use only 50/50 concentration of ethylene glycol type antifreeze and water."
The previous owner seemed to have most of his service done by a Plymouth dealer. Could the dealer have substituted the DexCool for some reason? Does DexCool make any kind of sense in this car? Why would they be so concerned that the mix be between 50/50 and 56/44?
If it makes any difference, the current coolant registered about -45F on my Prestone plastic tester (the kind with the large red plastic needle indicator). I plan to replace the coolant soon anyway.
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<snip>

How do you know it is DexCool? There are a number of different coolant formulations that are pink/red/orange in color, among them would be MoPar long life coolant.

DexCool, no. Long life coolant, yes.

Assures adequate freeze protection, adequate corrosion protection, adequate heat transfer, seal life.

What makes a difference (to me) is using some cheap $3 tester to check your coolant. Refractometers are pretty cheap now.
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aarcuda69062 wrote:

I'm glad you asked, even if I will look silly now. Among the things we got with the car was a partially filled bottle the pink stuff by Prestone (the silver bottle), which tells me the owner and not the dealer put it in. I knew there was some reason the word stuck in my head (the bottle says something about compatibility with DexCool).

For my purposes it has to last one year.

I don't see the problem with 60/40 or 65/35 or even 70/30 in that regard.

Wow. I haven't even seen a refractometer since the sixties, when I worked pumping gas at a station. Had a "turkey baster" specific gravity tester but don't know what became of it. I'll have to look around for a nice refractometer now.
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Wrong. Heat transfer starts to fall off rapidly after 55 solution of either ethynene or propylene glycol. Seals begin to leak due to low surface tension and solvent action of excessive glycol. Ethylene is acetic by nature; having too rich a mixture of it will promote electrolysis and corrosion even with the additive package that comes with it.

A good investment. The hydrometers (the better ones) can be fairly accurate IF the coolant hasn't been contaminated. The $3 plastic things are useless, as are the "floating ball" things. It's getting very hard to find good hydrometers for battery service now, as well. I used to order my hydrometer parts directly from C&D (one of the big 3 battery makers in the US,) but they've since replaced their old Pyrex hydrometers with cheap plastic ones.
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wrote:

Sorry, Bob, but I have to challenge this one. Ethylene (and I assume you meant to write 'ethylene glycol') is not 'acidic' by nature. But its oxidation products are, as are most oxidation products. (That is why the old German chemists called oxygen 'suerstoff' or acid maker)
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clifto wrote:

Why did you write "glycol vs. DexCool" when DexCool and almost every automotive coolant are primarily ethylene glycol (a few, like Sierra, are primarily propylene glycol)? The difference between DexCool and other coolants is in the anti-corrosion additive package, and DexCool lacks phosphates and silicates, the latter being part of the Alugard package. I'd use major brand universal or G-05 coolant in a Chrysler. The reason for limiting the concentration to 56% antifreeze is because ethylene glycol conducts heat only about 50% as well as water does, so too high a concentration can lead to overheating.
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clifto wrote:

I seriously doubt that. It was probably Mopar-brand G-05 coolant, which is also red (for some reason known only to the Mopar parts department, other G-05 brands are a pale gold/yellow).
The

OK, fact check time. ALL coolants (except Sierra and other Propylene-glycol based "low tox" coolants) are ethylene glycol based. Including DexCool. What differs between coolants is the anti-corrosion additive package. These fall into 3 categories:
1) Traditional silicate (the old Prestone type, usually green in color, but color no longer is definitive).
2) Hybrid organic acid technology coolants (aka HOAT). The most common example is G-05, used by Chrysler, Ford, Benz, and a bunch of European makes as OEM coolant. It has much lower silicate than traditional, but still has SOME.
3) Organic Acid Technology (like DexCool) which has no silicates.
The most nearly "universal" type is #2- the HOAT coolants. The least universal is #3. DexCool has caused huge problems in cooling systems not designed to use it, and even in quite a few that GM had allegedly designed for it. Your 94 Acclaim originally came with a silicate coolant, and that will be fine to continue using (most parts-store "house brands" are silicate coolants, made by Old World Industries (parent company of Peak antifreeze). But it will also be fine using G-05, available under the Mopar, Motorcraft Gold, and Zerex brands. Whatever you do, do NOT use DexCool in it, though.
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