The Use Of Ethylene Glycol In Our Radiators

I have seen several posts as of late of folks replacing propylene glycol (Dexcool) with the older ethylene glycol.

We should discourage folks from making this switch as I believe it is a mistake.

https://www.hemmings.com/blog/2014/08/01/tech-101-the-colors-of-antifreeze/

Not mentioned in the article is the boiling point of the two coolants. Ethylene Glycol (green) has a boiling point when mixed 50/50 with water of 250 degrees.

Propylene Glycol (Dexcool) has a boiling point when mixed 50/50 with water of 265 degrees.

GM introduced Dexcool in 1995 and has redesigned the cooling systems to take advantage of this coolant and takes the higher boiling point into consideration in computer programming and engine design.

Nuggets from the article:
1. Lasts longer
2. Friendly with aluminum radiators and heads
3. Not so friendly with copper radiators and lead solder
4. Hoses last longer, see ECD in the article
5. Ecologically friendly

Many of the horror stories attributed to Dexcool stem from ignorance. Folks topping off their Dexcool equipped vehicle's radiator with ethelyne glycol or too much water over time ruining its 50/50 balance which lowers the boiling point and longevity of the fluid. Not to mention creating that awful sludge that clogs the coolant passages in the block and radiator core.

Mine own experience with Dexcool vehicles has been positive. Most of the cars have had zero cooling system issues or needed maintenance over the last 20+ years, not even a radiator hose.

Remember all the radiator hoses we changed when we ran the green stuff? Comments?

old dex used to sludge up if it came in contact with air. the new formula does not do this i hear.

its not to be mixed with other coolant types either. unless universal coolant.

my regal was sludged up good from the old dex. when i tore that engine down the slime was everywhere. boogers floating in the rad too. the cap was always full of brown slime too. that cars been flushed to clean water and swapped to green years ago now.

swathdiver said:

Mine own experience with Dexcool vehicles has been positive. Most of the cars have had zero cooling system issues or needed maintenance over the last 20+ years, not even a radiator hose.

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Swathdiver -- Just reading this old post after starting a new thread today about whether it's necessary to change radiator hoses on my 146K, 2008 Yukon Denali if there aren't any soft spots present. Coolant was flushed at 65K, but will need to be changed due to the 5 year mark this summer. Is it ok the leave original hoses in place and just flush again?

KATfishing said:

Swathdiver -- Just reading this old post after starting a new thread today about whether it's necessary to change radiator hoses on my 146K, 2008 Yukon Denali if there aren't any soft spots present. Coolant was flushed at 65K, but will need to be changed due to the 5 year mark this summer. Is it ok the leave original hoses in place and just flush again?

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I would check each hose and squeeze them, if any are hardened or make a crunch its time to replace

Dexcool is not propylene glycol:
http://partimages.genpt.com/partimages/728572.pdf

It is still ethylene glycol. What makes the difference between Dexcool and others is the buffer system that prevents the coolant from becoming acidic. Acidic coolant will react with metals, especially aluminum. Dexcool uses an organic buffer which could polymerize causing the sludge. As long as it's not allowed to go acidic, it's a good coolant.

Most of the trouble with Dexcool seemed to be with the 3.8L motor, and maybe a few others. There were some faulty radiator caps which didn't seal well. As the engine cooled, it sucked air in through the cap, but the reservoir remained full. The additional air oxidized the ethylene glycol under the heat of the engine, forming acids.

Now, the acids do eat the aluminum, but the acids and high heat also slowly broke down the nylon framed gaskets. Because the 3.8L had coolant ports running through the lower intake gasket, the gasket would eventually fail, causing coolant to spill into the intake ports. Ford tried Dexcool in one of their cars for one year and found it ate their aluminum water pumps. So Ford went with G-05 coolant which, IMHO, is a better coolant. The buffer is based on borate rather than an organic molecule. So, there is no polymerization. The buffer is probably more stable at high heat than the organic buffer as well.

For the V8's, at least my 5.3L, there is no coolant going into the intake manifold. So there is no danger of an internal leak like they found in the 3.8L. However, I wonder if Dexcool may be contributing to the failure of the nylon heater hose connectors, and the nylon tanks of the radiators. At least, these are easy to fix, and less likely to do damage, as long as you don't drive the engine without coolant. I changed my 3.8L to G-05, but I haven't bothered to switch the Tahoe.

Fun story, when I was flushing the coolant in my old envoy, I assumed the dexcool bottle I grabbed at Oreilly was 50/50 premix. I loaded it into the radiator, and boom ready to go. For some reason or another I had an odd feeling, and looked at the bottle again and realized my mistake that it was full concentration. Woops. lol.

That said, I was good for up to what, like 350 degrees right??????

When I blew one of my T fittings last month all I had in the truck to dump in to get me home was a case of Bud Light.

Larryjb said:

Now, the acids do eat the aluminum, but the acids and high heat also slowly broke down the nylon framed gaskets. Because the 3.8L had coolant ports running through the lower intake gasket, the gasket would eventually fail, causing coolant to spill into the intake ports. Ford tried Dexcool in one of their cars for one year and found it ate their aluminum water pumps. So Ford went with G-05 coolant which, IMHO, is a better coolant. The buffer is based on borate rather than an organic molecule. So, there is no polymerization. The buffer is probably more stable at high heat than the organic buffer as well.

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I was handed down an Olds Intrigue, and had this exact problem on the 3800.

Is Dexcool the name for the pink stuff?

joe