Someone mixed Dexcool and Green in my '03 Chevy

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I've got a '03 Chevy Express 3500 6.0L with 110k miles which I've owned since new. Being a work van, couple of my guys have driven for extended periods of time. It has been leaking coolant for a while. At some point, the guys must of topped it with green coolant as the reservoir had green coolant. I just put in a gallon + of the green in it so my dad could go fishing.

I am going to find the source of the leak and fix it this week. I want to make sure my coolant system is completely flushed and filled with the best and most appropriate coolant.

Couple questions:
1. What is the best method for flushing the coolant and cleaning the system?

2. What coolant should I use

Thanks!
 
1) Drain and fill with distilled water repeatedly until you have 100% water in there. Then drain and add half the system capacity with undiluted coolant, then top up with distilled water.

2) Use the coolant currently recommended by the manufacturer for your exact vehicle. It will be the one most compatible with the composition of your system.
 
Last edited:
Originally Posted By: SteveHarper
1) Drain and fill with distilled water repeatedly until you have 100% water in there. Then drain and add half the system capacity with undiluted coolant, then top up with distilled water.

2) Use the coolant currently recommended by the manufacturer for your exact vehicle. It will be the one most compatible with the composition of your system.


Thanks for the quick response. I'm researching now on the best way to flush the system at home. I'm sure I'll have some questions.

As for using the Dexcool, I've read some people using stuff that is off the shelf at auto parts stores? Prestone? Super Tech? I guess these are compatible Dexcool alternatives? The benefit being less cost and readily available. Plus, the dealers around here are not the friendliest to the wallet.
 
Originally Posted By: HiccaBurp
Originally Posted By: SteveHarper
1) Drain and fill with distilled water repeatedly until you have 100% water in there. Then drain and add half the system capacity with undiluted coolant, then top up with distilled water.

2) Use the coolant currently recommended by the manufacturer for your exact vehicle. It will be the one most compatible with the composition of your system.


Thanks for the quick response. I'm researching now on the best way to flush the system at home. I'm sure I'll have some questions.

As for using the Dexcool, I've read some people using stuff that is off the shelf at auto parts stores? Prestone? Super Tech? I guess these are compatible Dexcool alternatives? The benefit being less cost and readily available. Plus, the dealers around here are not the friendliest to the wallet.


You can go aftermarket but get something approved. Zerex usually is. But remember, it's going to be in there for at least 3 years once you're done, so saving $5-$10 should not be your priority.
 
Originally Posted By: SteveHarper
You can go aftermarket but get something approved. Zerex usually is. But remember, it's going to be in there for at least 3 years once you're done, so saving $5-$10 should not be your priority.


Probably right.. I'm sure this thing holds quite a few gallons. Can you get Dexcool(real stuff) anywhere else besides stealerships?
 
Originally Posted By: HiccaBurp
Originally Posted By: SteveHarper
You can go aftermarket but get something approved. Zerex usually is. But remember, it's going to be in there for at least 3 years once you're done, so saving $5-$10 should not be your priority.


Probably right.. I'm sure this thing holds quite a few gallons. Can you get Dexcool(real stuff) anywhere else besides stealerships?


http://www.valvoline.com/products/brands/zerex/antifreeze/41
 
I'm sorry guys I can't co-sign Dexkill. I would suggest G-05 formula coolant. Any brand you want, they will all work equally the same. Day in and day out I repair cars, and whether or not it is caused by correct maintenance or not, Dexcool is garbage. By far the most coolant related problems I see are from GM's.
 
There's nothing wrong with the coolant. The problems were with the early gasket designs not being compatible. Heck, even Ford is moving towards dex-cool. It's the best at corrosion protection.


As far as brands, I second zerex. Probably one of the best aftermarket ones. Although AFAIK, any brand stating it's "dex-cool" has to meet the requirements. The ones to avoid are the "universal long life." that's usually dex-clone, and not as good.
 
Originally Posted By: HiccaBurp
As for using the Dexcool, I've read some people using stuff that is off the shelf at auto parts stores? Prestone? Super Tech? I guess these are compatible Dexcool alternatives? The benefit being less cost and readily available. Plus, the dealers around here are not the friendliest to the wallet.


Alternatives and using anything readily available is what got you into this. Forget that methodology, there is no benefit, just misery long term. Pay for the right coolant, drain from the radiator. Its changed so infrequently, every 50-60k or so, may as well do it right.
 
Originally Posted By: Joseph_S37
There's nothing wrong with the coolant. The problems were with the early gasket designs not being compatible. Heck, even Ford is moving towards dex-cool. It's the best at corrosion protection.

Naah, nothing wrong with Dex-cool..

Wait, what? That red sludge in your radiator? Oh, thats a bad gasket design, move along people, nothing to see here.
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Originally Posted By: HiccaBurp
I've got a '03 Chevy Express 3500 6.0L with 110k miles which I've owned since new. Being a work van, couple of my guys have driven for extended periods of time. It has been leaking coolant for a while. At some point, the guys must of topped it with green coolant as the reservoir had green coolant. I just put in a gallon + of the green in it so my dad could go fishing.

I am going to find the source of the leak and fix it this week. I want to make sure my coolant system is completely flushed and filled with the best and most appropriate coolant.

Couple questions:
1. What is the best method for flushing the coolant and cleaning the system?

2. What coolant should I use

Thanks!



Only use Dex. Your truck will be just fine, and it's so good even Ford is using it now.

Be VERY careful refilling this vehicle, as there is a specific procedure. Otherwise you may overheat or blow a head gasket!
 
I am going to have to agree with everybody that Dex isn't bad. It was the gasket design and material that was the issue. I have one of those engines with the bad design (3.4 V6) and have since replaced the headgasket and switched my coolant to Peak Global (not the all makes but the gold bottle.) It isn't approved for Dex but is listed as an alternative to it (according to PEAK.) So far it has been running excellent in my SUV. Clean and the test strips have come back A-OK.

Zerex is great but can be hard to find in some areas. Prestone is certified and Texaco/Havoline is also. T/H is the O.E. brand. Either of those is fine if you want to stay with Dex
 
Originally Posted By: SteveSRT8
Originally Posted By: HiccaBurp
I've got a '03 Chevy Express 3500 6.0L with 110k miles which I've owned since new. Being a work van, couple of my guys have driven for extended periods of time. It has been leaking coolant for a while. At some point, the guys must of topped it with green coolant as the reservoir had green coolant. I just put in a gallon + of the green in it so my dad could go fishing.

I am going to find the source of the leak and fix it this week. I want to make sure my coolant system is completely flushed and filled with the best and most appropriate coolant.

Couple questions:
1. What is the best method for flushing the coolant and cleaning the system?

2. What coolant should I use

Thanks!



Only use Dex. Your truck will be just fine, and it's so good even Ford is using it now.

Be VERY careful refilling this vehicle, as there is a specific procedure. Otherwise you may overheat or blow a head gasket!


"specific procedure"??? please share?? Where can I find it easily and without buying a whole service manual? I don't want to screw it up!!
 
You must remove the top hose and fill the system from there (into the hose). Once you get the block filled the level will come up in the radiator, then you reattach the hose and fill through the cap.

Don't simply fill the radiator and start it up. Watch the temp gauge like a hawk as it warms up.

Good luck!
 
Originally Posted By: Bgallagher
I am going to have to agree with everybody that Dex isn't bad. It was the gasket design and material that was the issue.

With regular green coolant the indentical engine and gasket combo, however faulty it may be, would never sludge the cooling system the way Dex-cool can.
 
Originally Posted By: Rock_Hudstone
Originally Posted By: Bgallagher
I am going to have to agree with everybody that Dex isn't bad. It was the gasket design and material that was the issue.

With regular green coolant the indentical engine and gasket combo, however faulty it may be, would never sludge the cooling system the way Dex-cool can.


True but dex has proven to be excellent at corrosion resistance etc against popular belief. If GM felt that they are better off replacing the coolant (versus fixing the cars with issues) then they would have made the switch to something new. Even Ford is moving in the direction of Dex. The sludging was because of air in the system and if it was ever mixed with anything besides dex. Plus regular green is hard to find now a days. Everything is the "all makes, all models" which is a varient of Dex. You are better of with a full flush and Peak Global or Dex fill.

I know I might have opened a can of worms by mentioning that Dexcool isn't bad but it really isn't in fact it is great in some engines. 2.2 ecotech is a prime example.
 
Originally Posted By: beast3300
I'm sorry guys I can't co-sign Dexkill. I would suggest G-05 formula coolant. Any brand you want, they will all work equally the same. Day in and day out I repair cars, and whether or not it is caused by correct maintenance or not, Dexcool is garbage. By far the most coolant related problems I see are from GM's.


My mechanic agrees with you Beast. My mechanic is not a fan of Dex Cool. My mechanic said it does get old and starts to gum up. I have a 2003 Chevy Cavalier that originally had Dex Cool in it from the factory and I do agree with my mechanic's opinion that Dex Cool actually does start to gum up when it gets old. My mechanic recommends to switch a car using Dex Cool over to the Prestone green antifreeze. I have a couple of close friends who have said their mechanics have said the same thing about Dex Cool and those mechanics prefer the tried and true green antifreeze. My personal opinion is completely flush your cooling system properly, refill with the proper antifreeze of your choice and replace the radiator and or coolant overflow caps with brand new caps from the dealer. New caps prevent problems and save engines! I have had radiator caps go bad. I have had caps bought from the local auto parts store not fit properly, so I buy these items from the GM dealer. The GM parts always work properly. Here is a quote from http://www.sancarlosradiator.com/dex-cool.htm :

"General Motors introduced Dex-Cool to certain lines of vehicles in 1996. Since it was formulated without the addition of silicates (the corrosion inhibitors in green antifreeze) a different corrosion inhibitor strategy was needed. Organic Acid Technology or OAT is the inhibitor part of dex-cool. Unfortunately, the dex-cool is capable a rather nasty breakdown. The residue it leaves behind is very sticky, and likes to find areas in the engine and other areas to "drop out" or "fall out " of solution and stick to the wall surface of engine and radiator. If the residue is in the radiator, hoses, or recovery bottle, it's relatively easy to clean and remove the debris. When the residue is in the heads and block, only a chemical flush will remove this orange mud. In some cases, the orange mud hardens, and seems to expand or push the gasketed surfaces out of position, causing leaks.
2002 Cad

No mileage claim here.

There are some in the industry (including GM) that claim that exposure to "air" causes the Dex-cool to come apart, and that faulty radiator cap design is the culprit. They say that with a faulty cap, the cooling systems allow evaporation, allowing the Dex-cool to destabilize, weaken, and lose it's already marginal protection, and then turn muddy. Others say that poor cylinder head design traps air in pockets, allows condensation and ultimately dilution, resulting in aluminum oxide formation and deposits. Neither of these theories completely explain the whole picture, and these are not a universally shared opinions. If air were the culprit, all Dex-cool systems in every vehicle with a recovery (overflow) container would suffer the same problem. They don't. Reverse flow V-8's would be immune. They aren't.

Most insulting about the whole issue is the GM dealer response to the problem. While the vehicle is still in warranty - turn a blind eye. Yet once the vehicle has gone past the warranty period, the solution is simple: replace the radiator, hoses, intake manifold gaskets and maybe the water pump. I believe it is this response that has spawned the current class action litigation.

There are about 72 brands of coolant on the market today. 95% of all these coolants are manufactured using ethylene glycol and mixed with 50% water when installed in a car or truck. Dex-cool is no exception. The differences between coolant brands comes from the additives that enhance the corrosion protection properties. For years this protection came from silicates, but more recently coolant manufactures have moved away from silicate enhanced coolant, to OAT enhanced coolant. Silicates are discussed more here.

Organic Acid Technology refers to the type of corrosion and rust inhibitors used in the make up of the coolant. OAT formulated coolants provide "background" or reserve protection (works like a vitamin), and as such, tend to react more slowly to situation changes as opposed to the faster acting silicates (works like an aspirin). There are several ingredients that constitute the OAT, including carboxyl, benzoate, borate, triazole, and 2-ethylhexanoic acid. Depending on the brand of coolant, these ingredients may vary. Vehicle manufactures increasingly are moving to OAT coolant, and may have slightly different formulations for different markets. European vehicles have used OAT formulated coolant with an addition of some low level silicates to provide further and faster protection. These are called hybrid inhibitor coolants because they contain both silicates, and OAT formulations. More discussion on coolant, inhibitors, and silicates are discussed here.

Dex-cool manufactures continue to insist that Dex-cool will last 5 years and 150,000 miles, and that the problem is lack of maintenance. In other words, you should be maintaining your maintenance free cooling system."
 
All baloney in my experience.

I own and maintain a fleet of GM vehicles including 3500 Savanas and Silverados. After having breakfast with the actual development engineer on the "G" team at GM in charge of vans I have stopped maintaining any factory Dex equipped vehicle until something breaks in the cooling system.

This is almost always in excess of 200k miles, and sometimes even more.

We have open recovery tanks on some and sealed recovery tanks on others. No difference, our factory Dex fill is clear and clean with NO SLUDGE of any kind.

The Dex thing is long over with, and is kept alive by misinformed folks on the Internet. Even Ford is using Dex now. Think about it.

Note that the OVERWHELMING majority of GM owners have had no issues since the bad gasket issue was resolved years ago.
 
Originally Posted By: SteveSRT8
You must remove the top hose and fill the system from there (into the hose). Once you get the block filled the level will come up in the radiator, then you reattach the hose and fill through the cap.


You should always capture and measure what comes out. If you fill it up and you're more than a pint short, there's too much air in there somewhere. Removing the top hose will either let that bubble push itself free, or let you back fill past a stubborn thermostat or water pump. Not just on LS motors but many cars now! Great procedure, too bad they make it so difficult so you can't refill in the field without tools.
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I like cars like my saturn with a 1/4" deaeration hose that goes from the top of the motor/ water outlet around to the surge tank. An automated version of this procedure.

To the OP, a lot of "green" coolant is a dexclone with OAT inhibitors, which will be close to dexcool anyway. One has to search specifically for silicated. If they bought generic antifreeze from a supermarket, gas station, big box store etc they probably got dexclone. Don't blame you for wanting it all out and a known quantity in, of course.
 
Originally Posted By: SteveSRT8
All baloney in my experience.

The Dex thing is long over with, and is kept alive by misinformed folks on the Internet.

Oh, of course, the $800 Dex-cool sludge repair bill on my mother's 1999 Monte Carlo at 52,000 miles was because of the internet..
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