# Reasons for not mixing G12 and green coolant?



## SeanBF (Aug 8, 2009)

I read somewhere in my manual for a 99 beetle that it is bad to mix the G12 VW coolant with green coolant. What are the reasons?








I was adding new green coolant into the beetle but after awhile I could see the liquid had turned pink and I am now afraid there was still remains of the G12 when I added the green.
Any help?
Thanks.
-Sean


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## gehr (Jan 28, 2004)

*Re: Reasons for not mixing G12 and green coolant? (SeanBF)*

G12 will solidify when mixed and the engine will need to be broken down to unclog it from all the passages in the head and block.


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## Krieger (May 5, 2009)

LOL, wow, im betting they designed it like this?


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## GT17V (Aug 7, 2001)

if you want to use green.... thorough flush the system with water until it drains clear. Then add green mix.
Though frankly... G12 coolant doesn't cost that much.
http://www.1stvwparts.com call them. Ask for Zeb.
Then drive to Auburn VW, in Auburn, WA to get the correct coolant for the car


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## geralddh15 (Sep 18, 2009)

If it has been mixed and there's already signs of compications (i.e. overheating) is tearing the motor down the only possible cure? Or could you do a coolant flush using a coolant system cleanser and coolang flush machine. Or is that still not enough? Reason I ask is I'm about to buy a vr6 that has this problem. Thanks for any info


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## vwpoorboy (Jul 11, 2005)

*Re: Reasons for not mixing G12 and green coolant? (SeanBF)*

the worst is when G12 and dex-cool are mixed... this = light brown milkshake for coolant.
Stick with G12. you should only need one gallon of it. personnally i use distilled water vs tap to avoid mineral deposits
Sorry to tangent, but I don't understand why people want to over engineer what real engineers spent ridiculous amounts of time and money on to figure out.
P.S. 
_Quote »_I was adding new green coolant into the beetle but after awhile I could see the liquid had turned pink and I am now afraid there was still remains of the G12 when I added the green.

^^this is because there was likely a lot more coolant left in the system than you knew of. it often hides in the engine and the heater core. like previously stated it is best to flush with water and then drain and mix in coolant (concentration depending on your winter temperatures)



_Modified by vwpoorboy at 9:59 AM 9-27-2009_


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## kungfoojesus (Jan 10, 2005)

g12 is silicate and phosphate free. it is designed specifically for alloy heads and engines. I would not use anything else. Non g12 coolant has the potential to corrode the cylinder head and gum up when mixed with other types of coolants. 
When mixed it becomes brown and coats everything with a sludge, like algae in a pond. Your expansion tank will show signs of this sludge. If it is all clean then you're in the clear, but I would certainly flush all the water out with a garden hose, then with about 10 gallons of distilled water, then add the proper mixture of g12 to distilled water. From here I would get the gravity of the coolant mixture tested to verify it is strong/weak enough for summer and winter.
Sorry but read the manual before you pour garbage into your VW. VW's are engineered which offers a lot of benefits (mainly to those that read the manual). Paying for all that engineering isn't worth it if you don't appreciate and respect it. In the end you'll just wish you had bought a toyota








VW's require a lot more attention to detail than the standard american or car imported to america. This is something VW is trying to change over the next decade but for now, read the manual and treat it like it asks to be treated... not like some other crappy import.


_Modified by kungfoojesus at 10:20 AM 9-30-2009_


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## Mile High Assassin (Aug 28, 2002)

*Re: (kungfoojesus)*


_Quote, originally posted by *kungfoojesus* »_
VW's require a lot more attention to detail than the standard american or car imported to america. 


I don't agree with that. Take any car and mix in the wrong coolant, you are asking for problems.


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## kungfoojesus (Jan 10, 2005)

Non g12 has potential to cause all kinds of failures in the alloy cylinder head of VW's. What other comparable car requires special phosphate and silicate free coolant? Yes, you can buy this stuff at the car parts stores NOW, but years ago it was a different story. Plus there will be 5 types of coolant on the shelf, MAYBE one of those is compatible with VW's. Sry, not the case with toyota or honda. You can pour chicken noodle soup into a toyota and it will still run for 100k miles.


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## Mile High Assassin (Aug 28, 2002)

*Re: (kungfoojesus)*


_Quote, originally posted by *kungfoojesus* »_Non g12 has potential to cause all kinds of failures in the alloy cylinder head of VW's. What other comparable car requires special phosphate and silicate free coolant? Yes, you can buy this stuff at the car parts stores NOW, but years ago it was a different story. Plus there will be 5 types of coolant on the shelf, MAYBE one of those is compatible with VW's. Sry, not the case with toyota or honda. You can pour chicken noodle soup into a toyota and it will still run for 100k miles.

Simply put, you are wrong. You mix coolants of different types and they react negatively with each other.


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## Michael Cahill (Mar 28, 2008)

*Re: (Mile High Assassin)*

Read here: http://faculty.ccp.edu/faculty...x.htm
(thats for an MK3, but you get the idea.
Mixing coolants = BAD
if you have already added a bunch of green to your pink, i would recomend flushing it out http://****************.com/smile/emthup.gif


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## Michael Cahill (Mar 28, 2008)

*Re: (Mile High Assassin)*


_Quote, originally posted by *Mile High Assassin* »_I don't agree with that. Take any car and mix in the wrong coolant, you are asking for problems.

Agreed.
DONT DO IT 
If its pink, add pink.
if its green, add green
if its blue, add blue.
any mixtures of the above colors... get it the hell outta there.


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## Mile High Assassin (Aug 28, 2002)

*Re: (Michael Cahill)*


_Quote, originally posted by *Michael Cahill* »_
Agreed.
DONT DO IT 
If its pink, add pink.
if its green, add green
if its blue, add blue.
any mixtures of the above colors... get it the hell outta there.

But likewise you need to be mixing in like COOLANTS not colors. The colors give you a general idea but I would read what type of coolant it is.


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## chewbacca5017 (Apr 20, 2007)

*Re:*

I had my "check coolant level" warning come on a couple months back.. so I topped off my coolant with what I had in the garage from my old car. The bottle specifically stated that it is safe to be mixed with all colors of coolant.
I checked the fluid and it looks fine... no sign of gunk or sludge at all. Am I missing something?
I'll make sure to pick up some G12 for the next time my coolant needs to be topped off. But really, I haven't noticed anything "off."


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## rob454 (Sep 18, 2009)

*Re: Re: (chewbacca5017)*

I think you should be fine. If it was the Prestone that you can add to all makes and models, that coolant is compatible with a wide variety of coolants. I have mixed that stuff with Dexcool and green stuff with no issues.


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## chewbacca5017 (Apr 20, 2007)

*Re: Re: (rob454)*

Yeah, I used Prestone to top-off my coolant. No issues.


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## ubhuato (Jun 6, 2009)

*Re: Reasons for not mixing G12 and green coolant? (SeanBF)*

I know i shouldn't post a question within a question but i flushed my whole coolant and i was just wondering if i should just stick with the g12 or if i can add regular stuff since it is completely flushed.


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## kungfoojesus (Jan 10, 2005)

*Re: Reasons for not mixing G12 and green coolant? (ubhuato)*

any silicate and phosphate free coolant will work, there will likely only be one of this type coolant on the shelf, be careful.


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## harmankardon35 (Sep 16, 2009)

is the yellow HOA (hybrid organic acid) prestone stuff safe? i seen a few of you guys say you use it. I have a few jugs of this stuff i bought to mix with dex-cool. Says it can be mixed with ALL types of antifreeze, but makes no specific mention of silicate or phosphates...


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## mk4_2.ho (Sep 23, 2004)

*Re: (harmankardon35)*

funny, my bottle of zerex dex-cool says it's compatible with g11/g12.
i've been topping off with it since 2000 (my dad runs chevy trucks) with no issues.
maybe it's isolated, but i don't get milkshake status when i do it, in fact my original coolant bottle is clear as a whistle.


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## CoolAirVw (Mar 8, 2007)

Here's a little video showing why you shouldn't mix antifreeze.

https://www.youtube.com/watch?v=eNr_moZHP4Y&t=1s


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## Butcher (Jan 31, 2001)

Typical mechanic/shop who does not listen to the customer complaint and starts to throw parts on a car to fix everything the client is not concerned about. Once you fleece the customer of all his money, then you find the root cause of original complaint. Now that you got the client over the barrel, they have no choice but to buy the radiator. That is why the automotive repair industry is known to be full of pirates. 

So sad. The funny thing is you show a video that proves it. The other sad thing is that you are Master ASE certified too.


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## CoolAirVw (Mar 8, 2007)

Butcher said:


> Typical mechanic/shop who does not listen to the customer complaint and starts to throw parts on a car to fix everything the client is not concerned about. Once you fleece the customer of all his money, then you find the root cause of original complaint. Now that you got the client over the barrel, they have no choice but to buy the radiator. That is why the automotive repair industry is known to be full of pirates.
> 
> So sad. The funny thing is you show a video that proves it. The other sad thing is that you are Master ASE certified too.


Maybe you missed the part of the video where I said, "TB was shot" or the part of the video where I showed the wear and the huge split in the belt? Or maybe you dont know that to diagnose a clogged radiator you have to drive the car and let it run for long periods of time. I had to drive it 20 min and it had to run in the bay for at least an hour to diagnose the issue. 

I certainly did listen to the customer. Your saying I should have ignored fact that the customer had no TB history, and ignored that the TB major had wear on the inner edge and I should have ingored the huge split in the belt, then drove it or left it running in the bay (for diagnosis) till the belt broke? Would I then have to pay for the major engine failure because it happened on my watch? 

Not to mention further test driving would have destroyed his trans. FYI we discussed the repair decisions with the customer, taking into account the belt condition, along with the recommendation from the dealer as well, and starting with replacing the TB-waterpump ect what we both agreed was the best plan of action. 

I'm very proud of the repair I did in this video. I stated in the video it gave me a great sense of satisfaction. If I would have diagnosed the radiator issue blindly without taking a "broad look" at the car the customer would have had a failed TB, with pistons crashing his valves, and a failed trans. This here is the value of a good mechanic. 

I would say your a typical part of the "internet mob" who is happy to find any detail that they interpret as wrong, and start crying "crooked mechanic" then crucify said mechanic without even taking all the facts into account. Did you ask how much I charged for diagnosing the radiator? Did you ask how much I charged for replacing the radiator? The answer to both those questions was zero. That isn't fleecing someone of their money. Diagnosing the problem, replacing the radiator, test driving and confirming the fix added 3 hours to the job and NOTHING was charged for that time. 

That being said, how about taking a look at my most recent video. When you find fault, since you are perfect you should cast the first stone.

https://www.youtube.com/watch?v=GaboTNGXsQw&t=37s


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## Butcher (Jan 31, 2001)

Coolairvw, maybe you missed the fact that you fleeced the client before you properly diagnosed the clients complaint.

You say you say the transmission may have been damaged on the road test, but you never thought that the lines were that way before it showed up to your place. You and I do not know if it could have lasted another year or a day. The fact is, it's been that way for awhile [assuming the lines were not done the day before it came to your shop] but you insisted that it would not last another minute. Way to go to scare the client into a repair.

As for the timing belt, yeah I get your point, it could have died at any second, but since the engine was already over heating, you insisted on cooling it down, replacing the belt and wear parts. Remember, it was already overheating before you found that out. You had to drive it for 20 mins for it to over heat? Really? Couldn't a IR temp gun showed you the radiator was hot in places? Even your hand could tell you that. You could have done that the first time you found the engine was overheating and way before you decided to see what kind of gold was under the timing belt cover.

You are a danger to the society. You have enough knowledge on how a car works and you use that knowledge to put fear into people so they have to fix the problems you find before you give them the answer to their original issue. What would of happened if the engine was overheated and ruined? Would you have sold the guy an engine too [after the transmission and timing belt repair] or would that have been the nail in the coffin and the client would wave the white flag? Then you would have scooped up the car for pennies on the dollar then sell it a few weeks later on your lot. 

It's shop owners like yours that really ruin my trade. You are despicable. You rip people off and prove it to yourself that you do not. You probably have been doing it so much that you cannot see what you are doing. I left a dealership after 24 years because of trade practices like yours. Someday I hope you can see what you are doing, but at this time, your focus is on money and not helping people at all.

Before you get on my butt, I never said that those parts were not needed. My big issue is that you *NEVER* focused on the clients concern, but your concern [$$$$].

Focus on the clients complaint. When you have that answer, then explain what the client needs BEFORE you do the repair. Give them a good overview of what is needed before you do anything. I do my best to give a client one call to tell them what their problem is and what the car needs. ONE CALL. I cannot imagine how many calls you made to them. So sad. 

I'm not certain what is worst, the fact that you know what you are doing and you like to fleece clients or the fact you have no clue and refuse to take advice that you may be doing it all wrong. As a diagnostic technician for most of my career, I look at all possibilities and evaluate all of them. I suggest that you take a look at yourself and business practices and see how that would work for you if you were the client. See what you could have done better with this client and think to yourself, maybe a quick IR gun to the radiator would have determined that the radiator had real issues. Way before you put that timing belt and trans cooler in. 

I've said my peace. If you have any other issues with my words, PM me.


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## CoolAirVw (Mar 8, 2007)

Your dead wrong. 

I'm a follower of the Lord Christ. The main reason I am no longer at my previous job with a big corporation, was upper management (uncaring corporate crooks) was pushing to for major repairs instead of minor fixes. 

I work hard every day to do a lot of what your saying. Diagnose the car right, never put money above people, do the right things for no other reason than because its right. Your principles are good and true, but your accusations are unfounded. 

I've said my Peace and I certainly have issues with your words!


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