Dexcool

[mechanicx]

Here is Zerex's product sheet for Dexcool. It lists very low waterpump cavitation corrosion, very low corrosion, almost non-existant corrosion of iron and aluminum. The most interesting spec is no-adverse effect on nonmetals.

Zerex Dexcool

Here is a thread on a Cadillac forum where one poster claims he has inside information that GM switched away from the plasticizer and Valvoline Zerex never had that Texaco's original Dexcool formula contained. I don't know how accurate this person claims are. I always believed that the potential plasticizer was 2-EHA. the poster mentions Preston Dex has it, and that makes sense because Prestone lists 2-EHA in its Dexcool and dexclone.

Cadiilac owners group Dexcool discussion

 

[SteveSRT8]

It's all moot to me as across over a dozen differing platforms and a combined (way more than) million miles I have never had an issue.

Heard about it a lot, but just never experienced it.

 

[defektes]

Dexcool (having suffered a IMG failure) is not so much to blame as the gaskets that it killed.

The original formula IMO destroyed weak gaskets.

Even in a maintained cooling system.

I will admit that my cooling system was spotless. Even with dexcool imo coolant should be changed at 2 years interval just to be safe. Needless to say I have regular old fasioned green in my 4.3

 

[mechanicx]

Originally Posted By: SteveSRT8
It's all moot to me as across over a dozen differing platforms and a combined (way more than) million miles I have never had an issue.

Heard about it a lot, but just never experienced it.


Abosulutely. I can understand some people not fully trusting Dexcool. But what they don't seem to consider is that many more vehicles don't show signs of problems with Dexcool.

 

[mechanicx]

Yeah I think Dexcool at least in it's original formula can be a problem in some applications. GM spent millions studying the issue and probably quietly made changes to Dexcool and engines. Dexcool I think is more of a standard than just just a specific formula.

 

[Dan55]

Here's an interesting read from 2001 http://www.taligentx.com/passat/info/fluids/Texaco-Havoline_DEX-COOL_Extended_Life_Coolant.pdf

 

[mechanicx]

Thanks that was an interesting read. I thought this stood out:
Quote:
The
American Society for Testing Materials (ASTM) has recently eliminated RA level requirements in
both key antifreeze specifications: ASTM D3306 for automotive engines and ASTM D4985 for
heavy duty engines. This action by the ASTM acknowledges that coolants which are not based on
phosphate and borate can provide excellent corrosion protection for cooling system metals.


Also:
Quote:
The primary limiting factor in the shelf life of a coolant is silicate instability. Since silicate will
eventually polymerize to silicate gel, all traditional coolants have a shelf life of about 18 months.
Havoline Extended Life Anti-Freeze/Coolant DEX-COOL®
is silicate-free and, therefore, can be
stored for at least 8 years without a problem provided the integrity of the container is maintained.


I am still slightly concerned about Dexcool's incompatibility with air in the system, and more concerned with its possibility to be more aggressive against some plastics and gasket. I'm not really concerned about cavitation-corrosion at least not in an application that was originally speced for Dexcool. I'm not really that concerned with Dexcool being intolerant of air either, if you keep the fluid level up and have a pressurized reservior.

The thing is what's not known is what changes in formulation have been done with which brands of Dexcool to eliminate those issues.

 

[mechanicx]

Here is another curious read. I think this might have been mentioned before. But if you look at the Zerex application chart, for the European manufactures Audi, Jaguar, Porsche,
Volkswagen, Land Rover Dexcool was approved for '96 up and AWAY from G-05. Granted it doesn't say this recommendation is automaker approved, but neither does it say the previous G-05 recommendation was automaker approved for those manufacturers prior to '96.

Also Saab is OEM approved to use Dexcool after '01 but that's probably because of GM. And of course Asian applications were recommended Dexcool in '96 and away from G-05.

Zerex coolant chart

 

[mechanicx]

Here is a read where Prestone was recently challenged before the BBB and ruled to remove its all makes all/models claim and refused to citing it's coolant met GM's GM6277M compatibility portion of the standard, and that GM6277M is the industry standard. I would like to get a copy of this standard but I think you have to pay for it.

Prestone all makes

 

[defektes]

I actually flushed my 05 silverado for the second time and went ahead and used dexcool in it again. partly due to warranty and partly due to it being a v8 with no history of IMG failures. I would still avoild dex in the various v6's that had the failures.

What I really want to know if the new versions of these v6s still have the IMG failures that they used to have back in the day.

 

[mechanicx]

Originally Posted By: defektes
I actually flushed my 05 silverado for the second time and went ahead and used dexcool in it again. partly due to warranty and partly due to it being a v8 with no history of IMG failures. I would still avoild dex in the various v6's that had the failures.

That is perfectly understandable.

Quote:
What I really want to know if the new versions of these v6s still have the IMG failures that they used to have back in the day.


They don't have the failures anymore. The LIM gasket was changed by '04. They don't seem to leak when the problem solver gasket is properly installed on older models either. Then around '05, the coolant was ran through a pipe bypassing the intake manifold I believe.

 

[wapacz]

Originally Posted By: defektes
I actually flushed my 05 silverado for the second time and went ahead and used dexcool in it again. partly due to warranty and partly due to it being a v8 with no history of IMG failures. I would still avoild dex in the various v6's that had the failures.

What I really want to know if the new versions of these v6s still have the IMG failures that they used to have back in the day.


and your v8 never will have a problem with the img and dexcool even if the img fails. That being because the v8 in your truck has no coolant running through the intake manifold. To my knowledge gm only produces one engine in the US that still has fluid going through the intake manifold and that is the 4.3 liter that they keep producing with out updating much.

 

[mechanicx]

FWIW, here is the GM TSB saying to only use licensed Dexcool, and to only use Dexcool, and listing the suppliers that are licenses. I think Zerex is also licensed now. And truth be told Prestone all makes/all models appears to be the same formula as Prestone Dexcool which is licensed.

Licensed Dexcool

 

[edwardh1]

wonder what the reason was for the change either in dexcool or in the gasket that caused the problem?
Why did they change from the "year before"

 

[Coolant_Man]

Originally Posted By: mechanicx
FWIW, here is the GM TSB saying to only use licensed Dexcool, and to only use Dexcool, and listing the suppliers that are licenses. I think Zerex is also licensed now. And truth be told Prestone all makes/all models appears to be the same formula as Prestone Dexcool which is licensed.

Licensed Dexcool

Zerex's version has its on patent...

http://www.google.com/patents?id=BRwIAAA...;q=&f=false

 

[mechanicx]

That's a good question and the real answer is probably hidden in GM's and Texaco's (and other Dexcool makers) files. Some people blame Dexcool's past problems on 2-EHA in Dexcool and distrust any Dexcool (or dexclone or OAT for that matter), but there's probably more to it than that.

GM just simply updated the intake manifold on some engines in the 90's and also switched to Dexcool. They also used a flimsy plastic manifold gasket on some engines that had a near 100% failure rate by within 100K-150K miles. The gasket probably would've not lasted no matter the coolant.

The question still sort of remains just how aggressive or not Dexcool is with certain gaskets compared to other anti-freezes.

 

[mechanicx]

I assume Zerex Dexcool is a licensed product. It's interesting to see that different Dexcool brands contain different formulas, and that Zerex claims better corrosion protection than some others. I skimmed through the patent and it made no real mention with regards to gasket or plastic corrosion/deteriation almost as if it's not even a concern. I did notice that it stated the formula's monocarboxylic acid could be based from 2-EH among other combinations of acid groups. Seems that all Dexcools may contain some level of 2-EHA for whatever that's worth.

 

[bigmike]

My question is why is GM demanding the usage of Dexcool when there are other products out there that fit the bill? I would much rather use Peak GL and I'm sure others would like to use other products such as G-05, but without the threats from GM to "void my warranty."

 

[Coolant_Man]

A friend of mine converted his new Chevy to Chrysler's G-05 which looks identical to the Deathcool he replaced. What GM doesn't know won't hurt them, lol.

EDIT...

@bigmike

GM created Deathcool and they make money licensing the name and formula to other companies so GM makes more money off of it. I guess it would be weird if they allowed you to use different coolant during warranty. It would appear their product is inferior. I think I have made my opinion known on that, lol.

 

[bigmike]

Fair enough. I have an extended warranty that won't expire until 2012 or 72k miles. I'm currently at 48k miles, so I'd like to keep within warranty. However, I have 4 gallons of Peak GL in the garage. I'm pretty set on changing it but I don't want any repercussions from doing so. This is why I've purposely waited and haven't done anything yet. I don't believe any issues will arise from using Dexcool in my application, but my past history with it has upset me enough to not bother giving them my money.

Maybe I should just shelve the Peak GL until the warranty runs out? Anyone know the shelf life?