DEX-COOL, Conventional Green, & G-05... My Experiences

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My family is a GM family. There have been a few exceptions to this. My Grandma's parents owned a Ford Model T, found out it was a piece of junk, and traded it for a Chevrolet. I owned a 1995 Ford Mustang GT for a few
months back in 1997 (great car). And my brother currently owns a Mitsubishi Eclipse.
I am the one that usually changes the coolant in my family's vehicles. I remember back around 1996 or so, I was driving a 1985 Chevrolet Monte Carlo and decided to convert it to the new red DEX-COOL coolant that had just came out. When I say "convert" I mean doing my 22 steps below as to obtain a 60% antifreeze to 40% water mixture. I later bought a 1991 Chevrolet Lumina and then a 1992 Chevrolet S-10 after owning several other cars between those and the 1985 Chevrolet Monte Carlo. I converted the Lumina to DEX-COOL. It ruined a gasket that had to be replaced. The S-10 was even worse. After converting it, it would blow smoke out of the tailpipe every time it was started due to coolant leaking into one of the cylinders.
I decided to get rid of the S-10 earlier this month and bought a 1995 Pontiac Grand Prix GTP with every option imaginable. After a few days of owning it, I checked the coolant to find that it was BROWN! That means it hadn't been serviced for quite some time. I figured it was DEX-COOL so I flushed the cooling system and poured in some fresh DEX-COOL. After doing that, I found out it had conventional green instead so, after about 3 days of DEX-COOL, I converted my car back over to green using Zerex 5/100 Coolant. I think I got the DEX-COOL out in time before it could start eating away at gaskets and seals and start spawning that reddish brown mud in my cooling system.
Now around 2000, I converted my Mom's 1995 Chevrolet Monte Carlo from green to DEX-COOL. After finding out about my Pontiac originally having green, I decided to convert her car back to green. I was SHOCKED to find that the DEX-COOL had turned into that damned reddish brown mud. The throat of her radiator and the radiator cap were almost ruined. It took me an good hour of scrubbing the radiator cap with a tooth brush to get it clean.
I did the exact same thing to her car that I had done to mine. I used the back flush tee I had installed in 2000, back flushed her car with the engine running with the heater on high for 30 minutes, poured in a bottle of Zerex Super Cleaner, had her drive the car on and off for about 6 hours, drained the radiator, back flushed again with the engine on and the heater on high for 15 minutes (I was happy to see the mud coming out knowing the Zerex Super Cleaner had done its job), poured in a bottle of Zerex Super Flush and ran the engine for 15 minutes with the heater on high to be sure all the mud was gone, drained the radiator, hooked the hose back up to the back flushing tee, and back flushed again for 30 minutes. I drained the radiator, took out the overflow tank and cleaned it out with hot water, Dawn dish soap, and a bottle brush. I hooked the overflow tank back up, closed the radiator drain plug, put the cap back on the back flushing tee, and poured in Zerex 5/100 Coolant.
That was about a 3 weeks ago. After checking the overflow tank, radiator, and radiator cap, I am happy to report that there is no mud and the car runs great.
All the above is my story with my experiences with DEX-COOL and conventional green coolant / antifreeze. I will now explain what I think of conventional green, DEX-COOL, and G-05.
DEX-COOL
I think this was a bad idea from the start. You would have to be a complete moron to run any coolant / antifreeze for 5 years. A lot of people also have the misunderstanding that they are not to touch it for 5 years. This is just stupidity created by GM.
I think the 2 biggest flaws to DEX-COOL are that if it gets into contact with conventional green directly or through the deposits left by conventional green, it will form that reddish brown mud. If DEX-COOL comes into contact with air either inside the cooling system or outside, it will form either the reddish brown mud or the red "cement". This has been proven by both owners of some 1996 - Present S-10s and owners of other GM vehicles.
I would probably recommend most folks stick with DEX-COOL if that is what their vehicle came with, but a lot of brave people have converted back to conventional green without any problems.
Conventional Green
I think it is the best especially for GM vehicles. If you do an extremely thorough back flush (the 22 steps listed below) you will get all the DEX-COOL out. I would HIGHLY recommend using Zerex 5/100 Coolant which most AutoZone stores carry.
G-05
I have not used this coolant yet, but keep hearing good things about it. It is designed to work in new Fords and Chryslers and has been used for many years by Mercedes and John Deere. I think GM will eventually switch to it.
Now if you would like to back flush the DEX-COOL or any other coolant out of your vehicle, do it this way (you are responsible for what you do to the vehicle you are working on).
1) Buy a few jugs of Zerex 5/100, either a Prestone or Zerex back flushing tee, a bottle of Zerex Super Cleaner, and a bottle of Zerex Super Flush. You might optionally want to go ahead and replace your thermostat.
2) After driving the car for 30 minutes or longer, open the radiator drain cock, and let the radiator completely drain out. While you are waiting, find the heater core hose that runs into the engine (not the one going to the water pump) and cut it. Install your back flushing tee. Also disconnect your overflow tank hose.
3) After the radiator is drained, take off the radiator cap.
4) Get your garden hose and screw it onto your back flushing tee connector then put the connector to the back flushing tee you installed..
5) Turn on the water and wait for water to start coming out of both the radiator drain and top radiator opening.
6) Turn on your engine with your heater running on high and let the car back flush for 30 minutes.
7) Turn off the engine and disconnect your garden hose.
8) Wait for the water to drain completely from the radiator.
9) Close the radiator drain cock.
10) Pour in your bottle of Zerex Super Cleaner into the radiator.
11) Connect the overflow tank hose and top off radiator with water.
12) If you have bleeder valves for air, turn the engine on with the valves open and wait for water to come out of them in a constant stream then close the valves.
13) Drive your vehicle for 4 - 6 hours which can be on and off and over a few days. Be careful the outside temperature is not 32 F or lower as water expands when it freezes which will ruin your radiator and your engine and other components.
14) Repeat steps 1 - 12 except for step 10 pour in your bottle of Zerex Super Flush.
15) Run engine for 15 minutes.
16) Repeat steps 1 - 9.
17) You may want to take out your overflow tank and scrub it inside and out with dish soap and a bottle brush. Be sure to rinse all the soap out of it. When you install it back into your vehicle, you may want to fill it up with water from your garden hose a few times and let it drain out through the disconnected overflow tank hose.
18) Connect the overflow tank hose after the overflow tank has been rinsed and is completely empty.
19) Pour in your jugs of Zerex 5/100 Coolant slowly until the radiator is full of coolant. If it takes 1 1/2 jugs, then that is 6 quarts. If your system holds 12 quarts, then you have a 50/50 mixture.
20) Fill the overflow tank with Zerex 5/100 Coolant until either the overflow tank is half full or you reach the HOT line.
21) Repeat step 12.
22) That is pretty much it, but be sure to check your overflow tank and keep the coolant level at the COLD line after your vehicle has sat for 6 or 8 hours over the next few days and get into the habit of checking it at least once a week.
Hopefully Helpful,
BTJustice
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Buford T. Justice wrote:

Snipped for space, not content

An excellent and informative post. You couldn't get me to touch Dex-Cool with a 50 foot pole due to some of the horror stories I've heard, but never seen anyone describe the hassles in any real detail. Thanks!
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That was what I was shooting for. Hope it helps you and others.
BTJustice

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98 bonneville 75k miles (5 year old coolant until just recently), Clean as hell coolant and overflow bottle. I pulled both my upper and lower intakes to repair a leak caused by the egr pipe and the cooling passages had NO oxidation, coatings, or sludge what so ever. The metal was as bright and shiny as the day it was assembled.

If its a silica based coolant it will eat up the aluminum components. Also the temp sensor is balanced to read a dexcool system. It may not have the resistance to the coating that green coolant leaves on everything. Though they make mistakes in designs now and then do you really know more about the cooling system than the GM engineers that designed it?

There is no steam in a correctly filled cooling system. You dont understand what I'm saying, I'll try my best to explain everything I have experienced and read about. Air in the overflow bottle wont muddy it. Its intense heat and low coolant levels that cause the coolant to crystalize. Basically when theres air in the system its cooking the coolant. Put salt water in a saucer and let it evaporate and you're left with salt crystals coating the saucer. Basically the same thing happens to dexcool and thats why it looks muddy because of air in the system and "intense heat". When you put non distilled water or another substance in the coolant it causes the chemicals that make up dexcool, to the best i can tell, fall out of suspension or to latch onto the contaminates or the sludge is the contaminate. If you're overflow bottle is muddy it was contaminated or your cooling system is low. When its low air is in the system and steam now builds up and pushes the coolant into the overflow bottle. Then all that crystalized coolant clogs up your radiator cap and what went into the overflow bottle doesnt make it back in so it tricks you into thinking your system is full. Thats why you need to uncap it now and then just to make sure its really full.

I do my own maintenance so its not impossible for me. Do what I do, keep it filled to the hot line when the engine is cool. GM is actually recommending that in their service bulletins. If some shop contaminates your cooling system pursue them in court if thats what it takes to correct that problem.
I got a website marked somewhere that covers dexcool and other coolants pretty well. If I come accross it in the next few days I'll post it. Dexcool is getting a bad wrap by people who dont try to fully understand it or dont maintain there systems correctly. If you never EVER contaminate an "original" dexcool system it wont get muddy. If you dont ever ever let air into the "COOLING SYSTEM" (not the overflow bottle) it wont get muddy.
You mentioned you tried to upgrade cooling systems that never originally had dexcool. The only possible chance that could have maybe worked is if the system was acid flushed repeatedly. Even then it would still be iffy.
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Glad to hear DEX-COOL is working fine for you. Others are not so lucky.

I have yet to see a green coolant sold at any major auto supply store that does not protect aluminum. The temp sensor doesn;t care what is in the cooling system. It simply monitors the temp of what is in the cooling system. Try running just straight water and you will see the temp is the same, but he water will start rusting your aluminum components. Texeco was the primary engineer of DEX-COOL.

Yes there is. How does a radiator cap open to let excess coolant into the overflow tank? Magic?

Now that is good advise. It is important ot remove the radiaotr cap from time ot time to be sure the radiator is actually full.

Keep the overflow filled to the HOT line on a cool system? That should tell the GM engineers are on crack.

DEX-COOL is getting a bad rap because GM didn't do enough real world tests on it. The simple truth of the matter is if DEX-COOL is in direct contact with air in one way or another then you will get mud. As I said, wait to a tennager at Jiffy Lube tops off your empty overflow tank with green. Do you really thing they will take your radiator cap off to look and see what type of antifreeze your are running? How about NO!

Super Cleaner being ran for 4 - 6 hours ring any bells? I and many uninformed people converted to DEX-COOL thinking it would last longer and be a better choice. Man were we wrong.
BTJustice
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"Buford T. Justice" wrote

No, it's not magic, but it's certainly not steam. It's simply the fact that the coolant expands as it heats, the rad cap is set to maintain 15 lbs of pressure in the system, once pressure goes past that, the cap unseats itself and allows coolant to flow to the overflow tank. Pretty simple stuff actually, no steam or magic involved.

Not really, it's just their way of trying to ensure that the cooling system does not get air into it for a longer period of time. The air in the system is really only a problem with any of the engines that have a cast iron block, or heads. I've seen very few if any sludging problems with the all aluminum engines. Also the vehicles that use a radiator cap, and a separate non-pressurized overflow tank seem to be the most susceptible to the sludging problem. I've seen very few problems with the vehicles that have the hard plastic pressurized overflow tank that has the 'rad' cap mounted on the overflow tank not the rad.

Of course, this is really more the fault of stupid customers that take their vehicles to a place like Jiffy Lube. And the problem is not Dexcool in direct contact with air, it's a cooling system that is allowed to be run at a low level for an extended period of time with an engine that has at least a cast iron block.

I don't believe that GM ever recommended changing to Dexcool on older cars.
By the way, I'm not a big fan of Dexcool. I work with vehicles that use it all day and I've come to the conclusion that it cannot be relied upon to last as long as GM says it should. We now advise people to change Dexcool at about the 100K kilometer mark, or every 3 years. This seems to work well, and cuts down on the incidence of cooling system problems with Dexcool.
Ian
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Yes and no. It is not complete steam but the beginning of the steam process that opens the radiator cap which is the cause of the pressure. If you open your radiator cap with a completely warm engine you will see what I mean when you see the steam and HOT coolant fly out.

Yes a lot of newer vehicles are losing the radiator cap altogether and simply running it on the overflow tank, but most cars still have a radiator with a radiator cap and an overflow tank that is non-pressurized. I honestly doubt the metal makes any difference, but I have heard the DEX-COOL does not like lead solder which use to be used for the metal lines going into the radiator.

As I said in my original post, my family is a GM family. However, I don't think the GM engineers deserve god-like status or anything. If the coolant is low in your cooling system, the idiot light on the dash should be on to alert the owner of this problem. I personally do most of the work on my vehicle. I might go to a Jiffy Lube in the dead of winter, and, when I do, I bring my own oil and filter. I only make them change the oil and nothing else. Thousand, and arguably millions, of people don't have the benefit of knowing how to do light maintenance on their vehicles and trust the places they go to 100% for that maintenance.

No, but Texeco, the co-creator of DEX-COOL, does. Look here...
http://www.havoline.com/products/na/antifreeze.html

Yes I believe changing coolant every 2-3 years is the smart thing to do. However, there really is no hope for DEX-COOL and GM is starting to realize this. Probably within the next few years, especially after this class action lawsuit over DEX-COOL, GM will either go back to conventional green, go to G-05, or come out with something completely different. Hope they don't make blue coolant. I can see someone pouring that into their washer fluid tank already.
According to the Zerex website below, their G-05 meets the current GM specs, but they do not recommend going over to G-05 from DEX-COOL though it is probably safe. Has anyone reading hits thread gone the G-05 from DEX-COOL?
http://www.valvoline.com/pages/products/product_detail.asp?product  (CLICK ON PRODUCT SPECS)
BTJustice
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Quick physics lesson:
A liquid under pressure under the absence of air will not boil or steam. As you pressurize a liquid, you increase the boiling point. as the boiling point increases, the pressure increases, and so on. This is why the boiling point at sea level is higher than say at 2000' elev. If you have coolant in your rad. at 15 psi. and it is even at 100 cel., it won't be boiling or steaming, because in a properly filled system, there is no air, therefore no room to make steam. Also, it is very important to not have air in your system because of cavitation, not just corrosion. You can't compress a liquid, and since your block is designed to have liquid in the galleries, not having it because of air is greatly weakening your block. Also, aluminum doesn't rust.

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Good, but I never said it was steam only that it was near the steaming process. Being near the steaming process creates pressure that eventually opens the radiator cap. Aluminum will not rust, but it will corrode. That is why most major coolant companies advertise that their coolant protects all metals from corrosion including aluminum.
BTJustice
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Joe Poitras wrote:

False.
A fixed pressure RAISES the boiling point, but if the engine gets hot enough it will boil coolant. Don't believe it? Just cut your water pump belt and run the engine for a while. By your theory, the coolant should never boil, right? Try it if you really believe that.... :-p
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|Joe Poitras wrote: | |> Quick physics lesson: |> |> A liquid under pressure under the absence of air will not boil or steam. | |False. | |A fixed pressure RAISES the boiling point, but if the engine gets hot |enough it will boil coolant. Don't believe it? Just cut your water pump |belt and run the engine for a while. By your theory, the coolant should |never boil, right? Try it if you really believe that.... :-p
The water will continue to expand until the resultant pressure overcomes the cap, then it will escape into the low-pressure atmosphere and boil. If you had a vessel able to contain the pressure of a quantity of water, no airspace, I think it would never boil. At least within the temps an IC engine could generate. Rex in Fort Worth
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If my rad cap stuck, then it wouldn't boil out until i ruptured a line, then there would be an immediate loss in pressure and then it would boil very rapidly, as the liquid would have been superheated (beyond it's normal boiling point)
In a lab in a pressurised environment, it is possible to heat water hot enough to glow from the heat.

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But it would still create pressure either rupturing a line or causing an explosion.
BTJustice

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Yes, but that pressure is not caused by steam, but by the liquid trying to expand when heated. A liquid under pressure caused by heating is trying every thing it can to boil, but because of the enclosed space, it can't.

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I would still think any liquid in the situation would boil if it got hot enough.
BTJustice

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Joe Poitras wrote:

See the part where I said "a fixed pressure" in the quote below?

See again the part about "a fixed pressure." Real-world radiators operate at a fixed pressure limit (say, 15 psi).

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No, the radiator cap allows coolant out simply because of the expansion of the coolant due to the increased temperature. There is not going to be any steam in there. The only reason why you get steam if you remove the radiator cap is because the drop in pressure that causes will lower the boiling point of the coolant and cause it to boil.
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And what causes that expansion? Heat. And what happens when you heat a liquid? It becomes hot and either starts the steaming process, or becomes steam, or becomes a gas.
BTJustice
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says...

WTH ARE YOU TALKING ABOUT STEAMING PROCESS??? IT HAS TO BOIL FIRST AND IT CANT UNDER 15PSI!!! It would have to reach 260 deg before it can begin to boil!
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This is the last time I am gonna explain this. As water APPROACHES its boiling point of 212 degrees Fahrenheit, the steaming process begins. That means the water / coolant is near the point where it turns from a liquid to a gas yet will not turn completely into a gas since it is not quite hot enough yet. However, there is some gas being put off. This is what creates the pressure that eventually opens your radiator cap.
Need more proof huh? OK, here is a very simple chemistry experiment. Take a glass and fill it almost to the top with water leaving a small space for air. Take plastic wrap and put it over the top of the glass so it is sealed. Now heat the glass and you will see the clear plastic either come off or loosen itself way before the water reaches its boiling point. What is this called? The start of the boiling process. This is basic high school physical science.
260 - 270 degrees Fahrenheit is about a normal boil over level for coolant. Boil over is where all hell breaks loose. But the coolant has starts to boil way before this but has not put out enough pressure to open the radiator cap yet. The whole thing is pressure. You are talking as if the coolant is pressurized at 15 PSI all the time which it is not. It only reaches this point after almost reaching a temperature to almost start it to boil (the beginning of the steaming process).
BTJustice
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