Preferred Antifreeze - JeepForum.com
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post #1 of 36 Old 06-12-2021, 02:45 PM Thread Starter
Cj7prm
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Preferred Antifreeze

What is the preferred antifreeze for a stock 1986 CJ7 with a 258. Stock radiator. The jeep is fairly new to me so I want to flush the system and put fresh antifreeze in. I plan to replace the T-stat while I'm at it.

Forgot to ask how many gallons I'll need?


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post #2 of 36 Old 06-12-2021, 02:57 PM
Techlight
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Well that depends lol...I usually buy a name brand but I've been known to dump in whatever I have on the shelf, but I have heard mixing brands isn't a good thing.

I usually also mix my own cause it's cheaper. If the block is completely empty should be about 4 gallons. Two gallons antifreeze, 2 gallons distilled water. I usually lean a little to the more antifreeze side cause I'm out in the desert.

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post #3 of 36 Old 06-12-2021, 06:51 PM
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Originally Posted by Techlight View Post
I usually lean a little to the more antifreeze side cause I'm out in the desert.
Hmm, I'd think you'd go the other way. You know water transfers heat better than antifreeze.

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post #4 of 36 Old 06-12-2021, 10:50 PM
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So why is it also called coolant?

50/50 and 70/30 are the low and high limits

I usually go with the 70 (coolant) 30 (Water)---any "Green Brand"

I mix it all at once before adding it to my Jeep, this keeps it 70/30 no matter what I pour in.

Too many folks add the whole antifreeze jug in, then top it off with water---with no clue what the mix really is!

70/30 allows for max protection and the possibility that I may have to add plain water should I get low my "Mix" is no where in sight.

I'd say my 258 system will hold right at 2 gallons total.

I highly recommend buying a "Lever Cap" for the radiator. this allows you to pick up the lever and relieve the pressure in the system before you do the "I'm Scalded Dance"

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post #5 of 36 Old 06-12-2021, 11:31 PM
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There are basically 2 types of anti freeze. There is ELC (Extended life coolant) or conventional. CJ's were made before ELC was introduced, but it can still be used with a freshly flushed system. ELC is nice because it lasts for years. But I just went with Prestone green conventional for my CJ5. With conventional anti-freeze you can simply use an inexpensive anti freeze tester at any time to see the range of operating temps that your fluid is still good for. I like to run mine with more then 50/50 because if it is rich then in the case of an emergency you can just add a little water and as long as it still tests good then nothing more needs to be done. Very convenient for trail use. With ELC you dont have that convenience or the ability to test it like conventional anti-freeze. A system with ELC needs ELC added, water wont do.


My 232 with a new 2 core radiator and new heater core took about 3 gallons.
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post #6 of 36 Old 06-13-2021, 06:24 AM
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Quote:
Originally Posted by JEEPFELLER View Post
So why is it also called coolant?





-----JEEPFELLER
It's called "coolant" because it is in the cooling system, it's called antifreeze cause its added to water to keep it from freezing.

Water 32 to 212
50 mix -35 to 232
70/30 mix -67 to 235

Antifreeze/coolant is designed to be added to water to extend the temp range of the water, mainly from not freezing and to lessen the corrosion of water.

Boiling point can be raised up around 232 with a 50 mix... but you can raise it to that with a higher pressure system also.

Ethylene Glycol is about half as good as a heat transfer medium than water.



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post #7 of 36 Old 06-13-2021, 08:43 AM
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Green is ethylene glycol based and is Inorganic Acid Technology or IAT, the orange or red are propylene glycol based, Organic Acid Technology or OAT. I work at a plant that makes both of these as a side stream from ethylene oxide and propylene oxide. Green is old school and will last about two years the other in newer technology and will last around five years. Water is your best cooling medium but will attack the metal and gasket materials so its not stable by itself. Neither ethylene oxide or propylene oxide offer protection against corrosion, they simply shift freezing and boiling points. The additives in the coolant, phosphates and such, is what protects the internals.

Talking to some Chem E's at work they say the two EG and PGs can be mixed with no problems, but the additives the manufactures use may not mix well. So if you have the green stuff in there and unless you can do a perfect flush, stick with the green. As for things like Water Wetter, its not a antifreeze, its and anticorrosion and lubricant design to be used in places where you do not see freezing weather, mixed with pure water or a lesser ratio of antifreeze to water.

At a 50/50 ratio, most antifreezes protect down to -34F. Do you ever see -34F where you live? If not then a 30% antifreeze / 70% water mix might serve you well ,just the amount of additives are going to be lesser and this is where folks will add some other corrosion/lubricant to help the system.

I personally run what ever was in the system to avoid incompatible mixtures and I do a 50/50 mix so there is not guessing required in case I need to add coolant. Green you get two years use, reds you get five.
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post #8 of 36 Old 06-13-2021, 08:48 AM
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JEEPFELLER in our little corner of God's green earth we should be more concerned about cooling than freezing. That extra 20% ain't getting you much in that direction. I don't think we are ever going to see -35 much less -67. Even when I lived in Omaha I always mixed it 50-50.

As to which brand I prefer it is what is on sale. I use the red because it is what I find on the shelf. I usually use the full strength and mix it with distilled water. Cheaper that way. That's more I can spend on ground wire!

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post #9 of 36 Old 06-13-2021, 10:43 AM
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70/30 allows for max protection and the possibility that I may have to add plain water should I get low my "Mix" is no where in sight. Yeah Bob!

What's all of this garbage supposed to mean?

-----JEEPFELLER
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post #10 of 36 Old 06-13-2021, 11:04 AM
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I don't think those gauges are a good reference... the low end shows 155*, which is too low. The next notch up shows 258*, which is too high of a temp for normal operating temps.

Its stating freezing and boil points which no matter how high your boil point is, 230 is hot, and it still doesn't change the fact that no matter what ratio your mix is, water transfers heat much better than "coolant/antifreeze".

Will a 70% coolant ratio work in the desert, sure, but a 40% coolant ratio would work better. He may have a 6 cyl with an oversized radiator so the capacity is plenty for the produced heat. Swap a 500hp V8 into the same system and you may be having temp issues with that ratio.

All I was saying is its recommended to run a 60 water/40 coolant in higher temp climates, not the other way around.

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post #11 of 36 Old 06-13-2021, 11:09 AM
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If your cooling system is not efficient enough to handle 70/30 anti freeze, then I would suggest that the anti-freeze is not the problem. And as Jeepfeller is demonstrating, a richer mix increases the boil over point. If you need to run cooler, try a cooler thermostat.
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post #12 of 36 Old 06-13-2021, 11:21 AM
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Quote:
Originally Posted by Dryseals View Post
Green you get two years use, reds you get five.

ELC can last a lot longer then that. I used to run a Diesel shop and there are little testing strips available similar to PH testing strips. We ran trucks for well over a decade on ELC and I never saw one of them that tested bad. I have also seen it made in black and blue colors, but it all works the same.
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post #13 of 36 Old 06-13-2021, 12:01 PM
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Quote:
Originally Posted by mudbfun View Post
If your cooling system is not efficient enough to handle 70/30 anti freeze, then I would suggest that the anti-freeze is not the problem. And as Jeepfeller is demonstrating, a richer mix increases the boil over point. If you need to run cooler, try a cooler thermostat.
Contrary to popular belief a "cooler" thermostat will not influence how cool an engine operates. It only allows the engine to begin/stop cooling when it opens/closes. It does nothing to prevent it from running hot. It will cause your heater not to function properly in the winter.

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post #14 of 36 Old 06-13-2021, 12:22 PM
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Originally Posted by JEEPFELLER View Post
70/30 allows for max protection and the possibility that I may have to add plain water should I get low my "Mix" is no where in sight. Yeah Bob!

What's all of this garbage supposed to mean?

-----JEEPFELLER
Different strokes for different folks!

As to what does all that garbage mean It beats the heck out of me. I figure that if the concentration--somewhere close to 50-50--is is good enough to keep it cool in the summer it will keep it from freezing in the winter. I do have the thingamajig to check the level of protection and if the temperature is going to be sub zero I'll use it. I'll have to clean out the mud dauber nest first.

I used to use plain old tap/creek/mud hole/whatever is handy water to mix or top off mine until I bought a new radiator for my old truck and the folks I bought it from told me they would only honor the warranty if I used premixed or distilled water. Been following that advice sense. When I had to take the Jeep radiator to a shop for repair--self inflicted--the shop owner mentioned how corrosion free the tubes were.

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post #15 of 36 Old 06-13-2021, 02:24 PM
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Quote:
Originally Posted by bob4703 View Post
Contrary to popular belief a "cooler" thermostat will not influence how cool an engine operates. It only allows the engine to begin/stop cooling when it opens/closes. It does nothing to prevent it from running hot. It will cause your heater not to function properly in the winter.

I understand the premise, but I don't entirely agree. If you are running a T-stat that is hotter then necessary, which some people do because of outdated emission standards employed decades ago, then it may be keeping the entire cooling system from working as effectively as it could be. And if we are going to get nitpicky about the efficiency of a specific coolant mixture for cooling purposes, then a well balanced thermostat is every bit as important.
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