# G12 Antifreeze Contamination



## rcprato (Sep 14, 2007)

I have a 05 Passat that I added Prestone Extended Life Antifreeze/Coolant to in the expansion tank which most of you probably know turned the G12 coolant a nice shade of brown. The jug of Prestone said compatible with all types of coolant and a phone call to Prestone also assured me it would be fine. My VW dealer service writer said that I need to drain, flush and refill system to prevent problems that will arise from mixing different types of atifreeze, can anybody verify that with something in writing from VW? I am having the work done today and Prestone may consider reimbursing me for the out of pocket expense if I can show them something from VW saying if another coolant has been added to the G12 and the result is the coolant turning brown, the system needs to be drained, flushed and refilled with G12 coolant.


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## Better Thomas (Oct 22, 2006)

*Re: G12 Antifreeze Contamination (rcprato)*

You should never add anything other than G12 to G12. You could ask your dealership if they will write something down for you stating that the Prestone caused problems. Any of our testimonies would probably not be admissible. Just for future reference, don't do it http://****************.com/smile/emthup.gif . It all kind of comes down to what is in the Prestone (yeah, that sounds simple enough).
G12 is free of certain chemicals (it skips my mind right now) but adding other coolants to it can add silicates and things like that (i think it's silicates?) and it'll mess stuff up.
My girlfriend added that junk to the Dex-cool in her car and it would get hotter than it was supposed to..she flushed (yeah, on her own) the system and refilled with Dex-cool, problem solved. So 'add it to anything' is bs.


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## AudiA4_18T (Mar 15, 2006)

so you have a Passat Passat?


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## brian1973 (Aug 17, 2007)

*Re: (AudiA4_18T)*

from what ive gathered from various tech articles, the difference is the use of neutralized organic acids or an "OAT" type.
Old "green" antifreeze doesnt use these chemicals. G12 and other long life fluids that say they can be mixed are cool to use because of "oat" chemical compatibility.
Now concerning what color you will end up with after mixing pink and orange or clear antifreeze fluids is up to the artistic persons.
VAG is,has, and always will be notorious for "dealer only products and services" which cost the owner thousands of dollars over the life of a vehicle. Its up to us and other mechanics to sift through the BS.
one reference= search car and driver for "antifreeze"


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## NOLA_VDubber (May 24, 2007)

*Re: (brian1973)*

I long ago switched over to prestone. Screw high-priced dealer-only crap


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## [email protected] (Nov 20, 2008)

*Re: G12 Antifreeze Contamination (Better Thomas)*


_Quote, originally posted by *Better Thomas* »_*You should never add anything other than G12 to G12.* You could ask your dealership if they will write something down for you stating that the Prestone caused problems. Any of our testimonies would probably not be admissible. Just for future reference, don't do it http://****************.com/smile/emthup.gif . It all kind of comes down to what is in the Prestone (yeah, that sounds simple enough).
.

you can always add distilled water. its supposed to be on a 1/1 mix with distilled water anyway, not straight g12


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## thetwodubheads (Dec 6, 2004)

*Re: G12 Antifreeze Contamination ([email protected])*

Color will be way off as you have seen, but I used it in my mother-in-law's older Jetta and it had no adverse effects. In small town Mt, you can't get G12 over the counter so we bought the "all makes, all models" stuff. Guy at the counter wanted us to use "Dex-Cool"







because it was the closest match to color. It does not gel, or cause excessive corrosion. Just don't use it like the 4 year G12. Flush and re-fill every year if you use "prestone."


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## TimFoley (Nov 22, 2010)

*HELP! just had the same experience*

I was driving home on a road trip and my coolant light blinked and beeped at me. Since a VW dealer was no where to be seen, I stopped at an AutoZone and asked for G12 grade coolant.

They didn't have it (said it was dealer-only stuff) and the store computer recommended Preston Extended Life 50/50 Prediluted Antifreeze/Coolant. 

I ate dinner and let the engine cool; opened the top of the ball and put ~1.5 cups (~400 mL) of this **** into the ball. 

I drove home, and checked the system today after researching the G12 coolant, and the ball has a 1 cm layer of brown emulsion!!!

Now I don't know if this is a result from mixing the two coolants, or if I have a small oil leak somewhere.

Is this common?

I just bought this car 3 months ago...it drives like a dream and has had no problems.

2000 VW Golf GLS (2.0L engine) with only 58K on the clock. 


The coolant seems to be a common question on VW forums, but I cannot find a complete answer. For the basic details:

it is phosphate and silicate free, and contains two organic acids (as stabilizers) including 2-ethylhexanoate.

I was in a rush and would have done an in vitro mix test first. AGGHH!


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## Bacon11 (Jan 20, 2010)

For what it's worth, the mechanic I go to was a head service tech for a VW dealership here before quitting and going into business for himself. He makes no money on parts (only his labor), and still recommends G12, and mixing nothing other than G12 with distilled water. 

He's got no affiliation with VW/Audi other than getting discounted rates on OE parts from the dealership.

Necro thread revive, too.


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## TimFoley (Nov 22, 2010)

*Chemically what's so special?*

. 

This brown emulsion/precipitate layer is floating on top of the liquid phase in the overflow reservoir. After evaluating the precipitate in the lab (thats right, I work in a chemistry lab), I can confirm that it is not an oil+water emulsion. The solution phase is pale orange/colorless. It appears that the colored dye is a constituent of the precipitated material, however I do not have an portion of unadulterated G12 coolant to do a mix test with in a tube.

After filtering out the small particulate matter in the coolant, addition of more Prestone Extended Life 50/50 did not induce further precipitation. It appears that the small portion I added did the deed entirely.

Unfortunately, I live in the city and have no garage or driveway to service my car in, and sold all of my tools before relocating. 


FML. Why do places not carry G12 coolant? That's strike one, VW.


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## NOLA_VDubber (May 24, 2007)

As I said back then when I first posted above in 2008, I've never had a problem mixing G12 with a "safe for all vehicles" pre-mixed coolant (I use prestone green). I'm not doubting that something is floating in your coolant ball, just that the mixing of coolants is what caused it.

Everything I've read suggests that the infamous gelling only occured when people made the switch from G11 to G12. As long as you indeed had G12 in your car, you should be fine. If you strongly feel the added coolant did cause some damage, I'm sure Prestone would be happy to foot the bill as their product plainly states its safe all vehicles.


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## TimFoley (Nov 22, 2010)

*trip to dealership*

as a followup:

I took my car into the dealership this morning. They flushed the system and refilled with G12 (G-012-A8G-1G); I also picked up some extra quantities of this coolant and a small bottle of powersteering fluid.

They also replaced the coolant reservoir that was covered and stained by the **** ($54.60 for reservoir, $54 labor)

and did a "MOC throttle body service" .... I'm assuming this is some sort of aerosol stuff to clean the oil gunk off of everything ($129 total)? We used to get this stuff from my friend who worked at Mopar.... 

I will test the compatibility of this newest G12 rendition with the Prestone and report back. This time I will be performing an in vitro test though. 

Thanks for the replies!

Tim


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## TimFoley (Nov 22, 2010)

*Prestone Extended Life antifreeze 50/50 premix miscible with G-012-A8G-1G*

I tested this with 50/50 diluted G12 (above) and everything seems happy. used ratios of 50:50 and 90:10 (Prestone:G12) to recreate the conditions in my coolant ball, and neither yielded a precipitate.

looks like my problem was either 

1.) old coolant that is not equivalent to G-012-A8G-1G and is incompatible with the above Prestone product

2.) some stopleak **** that had been added previously (unlikely, the service records for the vehicle are impeccible)

3.) oil in my cooling system (we'll see if this manifests itself with the fresh batch of coolant)

4.) a 'top up' that was performed at a no-name oil change facility where they put some incompatible antifreeze in.


needless to say, I wish I had my own garage to do my own work. se la vie.


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## Bacon11 (Jan 20, 2010)

If you do an invitro test in a bowl or bucket or something, that doesn't simulate the heat the coolant is subjected too, along with the cavitation from the pump and whatnot. Not sure if it's an accurate recreation.


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## NOLA_VDubber (May 24, 2007)

TimFoley said:


> I tested this with 50/50 diluted G12 (above) and everything seems happy. used ratios of 50:50 and 90:10 (Prestone:G12) to recreate the conditions in my coolant ball, and neither yielded a precipitate.


Good stuff :thumbup:


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## TimFoley (Nov 22, 2010)

Bacon11 said:


> If you do an invitro test in a bowl or bucket or something, that doesn't simulate the heat the coolant is subjected too, along with the cavitation from the pump and whatnot. Not sure if it's an accurate recreation.


I placed the samples (in sealed test tubes) in a beaker of boiling water for 30 minutes and yielded no change. only player missing is the trace amount of aluminum oxide that would be dissolved off the engine block.

it's also noteworthy that both solutions of working strength coolant were basic (pH 8-9)by pH paper (not willing to stick the pH probe in them) and the combined mixtures maintained similar pH values.

I'm going to yield to the fundamentals of solubility at this point, and confirm that these two coolants mix. However, after the $440 bill to flush my cooling system, replace the coolant ball, and have my oil changed, and that this was the result of mixing coolant; I have to say that I will NEVER again use anything other than manufacturer-certified fluids in my vehicle.


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## bootymac (Apr 19, 2005)

TimFoley said:


> I placed the samples (in sealed test tubes) in a beaker of boiling water for 30 minutes and yielded no change. only player missing is the trace amount of aluminum oxide that would be dissolved off the engine block.
> 
> it's also noteworthy that both solutions of working strength coolant were basic (pH 8-9)by pH paper (not willing to stick the pH probe in them) and the combined mixtures maintained similar pH values.


You are officially awesome. Thanks for testing this and sharing the results :thumbup:


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## terror_Storm (Jul 7, 2010)

TimFoley said:


> I placed the samples (in sealed test tubes) in a beaker of boiling water for 30 minutes and yielded no change. only player missing is the trace amount of aluminum oxide that would be dissolved off the engine block.


The cooling system is under pressure, too.


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## TimFoley (Nov 22, 2010)

Pressure generally has a negligible effect on on the solubility of substances presented to a liquid in a condensed phase of matter (i.e. liquid or solid).


There's not a whole lot else that can be said about this, except that I would really not mix the coolants, and the price of the G12 ($23) is not that much more than buying extended life coolant; and the hastle of dealing with a mishap is totally not worth saving $5. everyone should have a bottle of this stuff in their trunk just in case.


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## Bacon11 (Jan 20, 2010)

I applaud how well thought out that was, but I still have to question whether or not the pump could mix them, similar to how you use a wisk to mix oil, vinegar and mustard to make salad dressing (mustard or something as an emulsifier... don't look at me like that, I like to cook :wave. 

Either way, well done. In the end, I'm not planning on mixed anything with my G12... I used a bottle and a half with water to fill up my car, so I've got a jug of pre-mix in my trunk in case I have a crack in another flange that drinks 7 gallons of water in 600 miles (like my drive home from h2o).


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## beaker420 (Oct 15, 2006)

any updates?? this is good stuff.


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## 87vr6 (Jan 17, 2002)

Yup, green coolant doesn't do anything adverse in modern VW motors...


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## [email protected] (Oct 7, 2008)

http://www.audizine.com/forum/showthread.php/263790-Antifreeze-Experiment-amp-Testing


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## K20017 (Nov 14, 2007)

87vr6 said:


> Yup, green coolant doesn't do anything adverse in modern VW motors...


So the green coolant eats VW's aluminum but not GM's? :screwy:


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## undwirtanzten (Feb 9, 2011)

terror_Storm said:


> The cooling system is under pressure, too.


in case you didnt notice, this experiment was done under pressure as well. when you heat a liquid, it expands (as dose anything else on this planet you heat up). when something tries to expand, and is in a sealed container, it builds pressure.


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## TimFoley (Nov 22, 2010)

undwirtanzten said:


> in case you didnt notice, this experiment was done under pressure as well. when you heat a liquid, it expands (as dose anything else on this planet you heat up). when something tries to expand, and is in a sealed container, it builds pressure.



cooling systems are generally held to 1 atmosphere above ambient pressure, the reason being that this increases the temperature that water in the coolant transitions to the gas phase (read: boils). Since I don't see a traditional radiator cap on the system stamped with a rated pressure, I can't state the precise pressure of the system, but I can assure you it is ~ 1 ATM. 

This subtle increase in pressure is enough to accomplish the job, but not of significant mangitude to affect the rate of the chemical reactions as you suggest. When we talk about pressure effecting such thing, it is generally on a scale that is exponents of 10 (e.g. 10, 100 or 1000 times the pressure).

Any suggestion that the above experiments are invalid because they were not performed "under pressure" are inaccurate.


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## crazyquik22023 (Jun 17, 2013)

Should u mix g12 with any other coolant? No. Will it cause significant engine damage if you do this? No. G12 should not be mixed with other coolants. You should only run one or the other. To the OP, you should just drain your coolant system, flush it out, and fill it with a 50/50 mix of g12 and water or prestone and water. G12 has its benefits but is also more expensive. The post above with the corroded cylinder head I guarantee did not happen from running generic coolant mixed with water. Mixing the 2 coolants can cause corrosion, premature wear on parts, weak heat, etc over time. All in all for $40 or so why would you not run g12 coolant? It is designed for the car and costs only a little bit more than the generic coolant. But if you do or have in the past run generic coolant it is nothing to worry about.


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## AmIdYfReAk (Nov 8, 2006)




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## rstolz (Jun 16, 2009)

Hey, I found this dead horse, wanna beat it?


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