Dexron Antifreeze mixing

[Vito Cavallo]

I have a 1997 Buick LeSabre.
I has the orange Dexron coolant. The car was not blowing heated air, so I
checked the radiator. The coolant level was very low, so I put in some
green Texaco coolant.
Can I mix Dexron and regular antifreeze, or will I blow my engine?

The car is in the repair shop for the coolant leak, but I want to know for
the future.

Thanx

[Robertwgross]

Post by Vito Cavallo
I have a 1997 Buick LeSabre.
I has the orange Dexron coolant. The car was not blowing heated air, so I
checked the radiator. The coolant level was very low, so I put in some
green Texaco coolant.
Can I mix Dexron and regular antifreeze, or will I blow my engine?
The car is in the repair shop for the coolant leak, but I want to know for
the future.

(1) Do you mean orange Dex-Cool coolant?
(2) Your heater may not have been blowing hot air since there was an air
bubble, due to the low coolant level.
(3) Mixing Dex-Cool with ordinary coolant is not wise. It won't blow the
engine, but you will have a big gummy mess pretty soon. If this is what you
did, then it would be best to flush the whole works, chemically rinse the whole
works, and then refill it with proper coolant. You can use Dex-Cool, or you can
use ordinary coolant, but don't mix them.

---Bob Gross---

[GMdude]

Vito,

Mixing Dex-Cool and green coolant is not recommended by GM. But the
green coolant can be added, when you are in a bind, and you don't have
Dex-Cool. It will not harm the engine, gel, or gum-up, as Bob has stated. It
will however reduce the life of the coolant, to that of the green coolant.

When you have your mechanic repair the leak, have him flush the cooling
system well, and re-install the Dex-Cool. No chemical flushing is needed, or
advised. Both coolants are of an ethylene glycol base. Dex-Cool has a longer
life, and is better for the environment.

I received the above information, from an instructor at the GM training
facility, in Hinsdale, IL, while taking a course. His information came from
an engineer in Detroit.

This myth of gelling-up, or gumming-up, is just that. A myth.

GMdude

[Robertwgross]

... This myth of gelling-up, or gumming-up, is just that. A myth.

However, it is a well-observed myth.

A close relative purchased a one-year-old GM car with orange Dex-Cool in it. It
looked clean and orange when he got it, but the level looked low, so he dumped
in some green normal coolant. Next think he knew he had a brown mess, kind of
frothy and bad. He did some checking around, and that kind of mixture problem
seemed to be well known.

---Bob Gross---

[GMdude]

Bob,

Dex-cool has been known to leave brown deposits in the recovery tank,
and at the radiator cap. That dose not mean there is a problem. Green
coolant also leaves deposits. They are usually light-green/white in color.
So what?

Any dye will leave some sort of residue. The green coolant isn't green
until the dye is added. The Dex-Cool isn't orange until the dye is added.
It's the dyes that leave a residue in the cooling system.

The dyes will not harm the engine. Even if they mix and make some nasty
color, the coolant is still OK.

It's not a well known problem. It's a well circulated myth. It might
make a nasty color, leave brown stains, but it doesn't effect cooling, or
the engine.

GMdude

[GMdude]

Bob,

When it comes to colors/dyes. When you mix orange with green, you get
brown.

GMdude

[Robertwgross]

Post by GMdude
When it comes to colors/dyes. When you mix orange with green, you get
brown.

NO JOKE!

That wasn't the issue. I think you missed my point. The question was what was
going on when you mix clear, orange Dex-Cool with clear, green normal coolant,
and shortly later you get this frothy mess. If it were clear and brown, that
would not be too surprising.

---Bob Gross---

[GMdude]

Bob,

Hey dude. I'm giving you the GM facts. I've added the green stuff to
orange, when the orange was not there. I found no froth, as you put it, and
no problems with cooling. I worked for GM for 10 years, and now work for a
municipality. I maintain a fleet of 126 vehicles, along with 3 other
mechanics.

These vehicles vary from cars, to 40 foot transit buses (diesels). I
doubt there is much you can teach me about coolant.

I currently have access to all GM service bulletins, which state nothing
to the contrary, of what I have stated here.

If you can show me any shred of evidence about this stuff causing engine
problems, when mixed with green coolant, then do so. Meaning GM
documentation.

Froth in a cooling system is usually a sign of a petroleum product mixed
in. Oil, trans fluid, etc...

GMdude

[DeathRat]

Post by GMdude
Bob,
Hey dude. I'm giving you the GM facts. I've added the green stuff to
orange, when the orange was not there. I found no froth, as you put it, and
no problems with cooling. I worked for GM for 10 years, and now work for a
municipality. I maintain a fleet of 126 vehicles, along with 3 other
mechanics.
These vehicles vary from cars, to 40 foot transit buses (diesels). I
doubt there is much you can teach me about coolant.
I currently have access to all GM service bulletins, which state nothing
to the contrary, of what I have stated here.
If you can show me any shred of evidence about this stuff causing engine
problems, when mixed with green coolant, then do so. Meaning GM
documentation.
Froth in a cooling system is usually a sign of a petroleum product mixed
in. Oil, trans fluid, etc...
GMdude

I too work for GM as a partsman. I found this on Dex-cool from GM Infonet.

Date Created: 02/21/2003
Last Updated: 01/13/2004

Author: Gayle Timmons/MINACSGM/CA

Reference: TAC TIP

Reference #: TT742

Document Title: COOLING SYSTEM ADDITIVES ON VEHICLES WITH DEX-COOL ENGINE COOLANT - TT742

Condition:

Cause:

Correction:

DATE: FEBRUARY 21, 2003
TO: ALL GENERAL MOTORS DEALERS
ATTENTION: SERVICE MANAGER/SHOP SUPERVISOR/
PARTS MANAGER
C: ZONE - ASSISTANT ZONE MANAGER - SERVICE
ZONE - DISTRICT SERVICE MANAGER
ZONE - DISTRICT PARTS MANAGER
SUBJECT: TT742 - COOLING SYSTEM ADDITIVES ON
VEHICLES WITH DEX-COOL ENGINE COOLANT
VEHICLES AFFECTED: ALL VEHICLES EQUIPPED WITH DEX-COOL
ENGINE COOLANT
FROM: P.C. BAGNALL, GENERAL DIRECTOR,
CUSTOMER SUPPORT SERVICES
ISSUED BY: RICHARD HORSLEY, SERVICE ENGINEER,
TECHNICAL SERVICES DEPT.
FOR FURTHER INFO: TECHNICAL ASSISTANCE CENTRE
- 1-800-XXX-XXXX - GROUPS 2 & 3 __________________________________________________________
***DISCLAIMER***

GENERAL MOTORS SERVICE INFORMATION MATERIALS ARE INTENDED FOR USE BY
PROFESSIONAL TECHNICIANS, NOT A 'DO IT YOURSELFER'. THEY ARE WRITTEN
TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME
VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER
SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT,
TOOLS, SAFETY INSTRUCTIONS AND KNOW HOW TO DO A JOB PROPERLY AND SAFELY.
IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE INFORMATION APPLIES
TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A
GENERAL MOTORS DEALER SERVING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR
INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.

CONDITION:

Use of Cooling System Conditioners, Stabilizers or Additives not required with DEX-COOL Engine Coolant.

CAUSE/CORRECTION:

Since 1996 most General Motors vehicles were produced with DEX-COOL long life engine Coolant. DEX-COOL, if properly maintained, will protect the engine cooling system components for a period of 5 years or 240,000 KM, which ever occurs first. This service interval will be met if the cooling system is properly maintained in the following three areas:

1. The cooling systems freeze protection and level must be maintained to prevent deposits from forming in the voids of the cooling system. Proper coolant strength and level are critical to preventing the formation of rust-like deposits in the cooling system.
2. DEX-COOL must not be mixed with conventional "Green" coolant. Mixing coolants will remove the extended life properties and require that the coolant be replaced or recycled at a 2 year/50,000 KM service interval.
3. The radiator cap must be maintained and tested on an annual basis as outlined in the vehicle maintenance schedule. A properly functioning cap ensures the cooling system pressure requirements are met as well as maintains proper cooling system level by allowing coolant to transfer between the reservoir and radiator.

Some companies are promoting products such as Conditioners, Stabilizers or Additives, which are claimed to improve or extend coolant performance or life. General Motors does not support or recommend any products, which do not meet General Motor’s specifications. The use of these products may degrade the cooling system and any resulting failures would not be covered by the General Motors New Vehicle Limited Warranty.

The vehicle owners manual section Service and Appearance Care, contains the following statement on cooling system additives: "Notice: If you use proper coolant, you don’t have to add inhibitors or additives which claim to improve the system. These can be harmful."

Proper cooling system maintenance and flush procedures are covered under Product Service Bulletin 06-02-006 DEX-COOL Engine Coolant Information

Previous Product Service Bulletins were released to assist technicians in identifying some cooling system conditions that were incorrectly diagnosed as a failure of the DEX-COOL coolant. These are:

1. PSB 99-06-02-012D - Relating to certain 1996 - 2000 S/T Pickups and Utilities with the 4.3 Litre V6 engines which were operated with a low coolant level.
2. PSB 01-06-02-003 - Relating to certain 1996 RWD Chevrolet Caprice, Buick Roadmaster and Cadillac Fleetwood with a 4.3 Litre or 5.7 Litre V8 Engine which could experience excess aeration of the coolant.
3. PSB 00-06-02-004 - Relating to certain 1996 - 2000 vehicles with 3.1 or 3.8 Litre V6 engines, which are operated with a low coolant level.
4. PSB 00-06-02-005 - Relating to certain 2000 Buick LeSabre or Pontiac Bonneville Models which could have excess deposits from coolant sealer pellets.
--
Sincerely, Alan Ralston
--

GM Partsman
Owner of Pure Performance Fever
http://www.bonnevilleattitude.com/store/
Owner of BA.Com Forum
http://www.bonnevilleattitude.com/forum/
--
Home Page: http://www.bonnevilleattitude.com/deathrat/

[John Tolman]

Post by GMdude
Bob,
Hey dude. I'm giving you the GM facts. I've added the green stuff to
orange, when the orange was not there. I found no froth, as you put it, and
no problems with cooling. I worked for GM for 10 years, and now work for a
municipality. I maintain a fleet of 126 vehicles, along with 3 other
mechanics.
These vehicles vary from cars, to 40 foot transit buses (diesels). I
doubt there is much you can teach me about coolant.
I currently have access to all GM service bulletins, which state nothing
to the contrary, of what I have stated here.
If you can show me any shred of evidence about this stuff causing engine
problems, when mixed with green coolant, then do so. Meaning GM
documentation.
Froth in a cooling system is usually a sign of a petroleum product mixed
in. Oil, trans fluid, etc...
GMdude

http://www.bigclassaction.com/settlement/general-motors-dexcool-antifreeze.php

[Steve W.]

Post by John Tolman

Post by GMdude
Bob,
Hey dude. I'm giving you the GM facts. I've added the green stuff to
orange, when the orange was not there. I found no froth, as you put it, and
no problems with cooling. I worked for GM for 10 years, and now work for a
municipality. I maintain a fleet of 126 vehicles, along with 3 other
mechanics.
These vehicles vary from cars, to 40 foot transit buses (diesels). I
doubt there is much you can teach me about coolant.
I currently have access to all GM service bulletins, which state nothing
to the contrary, of what I have stated here.
If you can show me any shred of evidence about this stuff causing engine
problems, when mixed with green coolant, then do so. Meaning GM
documentation.
Froth in a cooling system is usually a sign of a petroleum product mixed
in. Oil, trans fluid, etc...
GMdude

http://www.bigclassaction.com/settlement/general-motors-dexcool-antifreeze.php

"The company, however, stated that in agreeing to settle, they don't
admit any liability and that they believed that Dex-Cool protected
engines for longer periods than traditional coolants. Company
spokespersons said that the coolant caused less wear on certain engine
parts and provided various environmental benefits. They also claimed
that owners who experienced engine and cooling system problems had not
followed maintenance instructions. "

[Steve W.]

Post by GMdude
Bob,
Hey dude. I'm giving you the GM facts. I've added the green stuff to
orange, when the orange was not there. I found no froth, as you put it, and
no problems with cooling. I worked for GM for 10 years, and now work for a
municipality. I maintain a fleet of 126 vehicles, along with 3 other
mechanics.
These vehicles vary from cars, to 40 foot transit buses (diesels). I
doubt there is much you can teach me about coolant.
I currently have access to all GM service bulletins, which state nothing
to the contrary, of what I have stated here.
If you can show me any shred of evidence about this stuff causing engine
problems, when mixed with green coolant, then do so. Meaning GM
documentation.
Froth in a cooling system is usually a sign of a petroleum product mixed
in. Oil, trans fluid, etc...
GMdude

The only thing I have ever seen from GM on mixing coolants was that is
acceptable to mix them BUT that it degrades the Dex-cools "Extended
Life" and meant that you needed to switch to the maintenance intervals
for the green coolant.

99% of the "coolant caused" gasket failures are NOT due to the coolant.
They are due to the piss poor gasket design combined with the poor
clamping of the parts. The SBC didn't have gasket failure issues till
the switch to the Gen 2 head/intake designs. Many people claim the 4.3 /
5.7 intake gasket failures are due to Dex. Nope they are due to plastic
gaskets and lack of even clamping forces.

[Dick]

Post by Robertwgross

Post by GMdude
When it comes to colors/dyes. When you mix orange with green, you get
brown.

NO JOKE!
That wasn't the issue. I think you missed my point. The question was what was
going on when you mix clear, orange Dex-Cool with clear, green normal coolant,
and shortly later you get this frothy mess. If it were clear and brown, that
would not be too surprising.
---Bob Gross---

The brown stuff has nothing to do with mixing in other coolant. It is
an issue with the Dex-Cool and has happened in several instances. The
main cause seems to be running too low on coolant.

You did not say what year that car was. There were problems with some
of the 1999 models. Perhaps some materials used in the engine were not
compatible with the coolant but GM has denied any connection. In all
cases they say that proper maintenance was the issue.

Problems seem to be especially bad with Dex-Cool when the owner lets the
level get too low or top off with water instead of a coolant mixture.

Some brown stuff that has been seen comes from leak preventatives.

It is important that you have Dex-Cool you should make certain the
over-flow tank is full at all times. Of course that is important with
all coolant but especially with Dex-Cool.

[Bon·ne·ville]

From what "I've experienced" and have seen the conventional green
coolant attacts aluminum towards the end of its life cycle vigorously.
I've seen some pretty bad pitting on machined mating surfaces of
aluminum. I've also seen hardened clusters of silicon bonded to aluminum
surfaces. The silicon contained in green coolant isnt the healthiest
stuff you can put in a modern cooling system. As the coolant ages the
silicon tends to bond to each other forming larger particals and it
begins to eat away at aluminum like a sand blaster. The aluminum pipes
on heater cores seem to often fail because of this. (my theory)
When ever you put a silicon based coolant in your cooling system you
must and I mean MUST change your coolant every 2 years. Even if you try
to switch back to dexcool. I can look at a system that has had green
coolant in it and it is coated with scaling even from short term use.
That coating "prevents" dexcool corrosion inhibitors from effectively
lasting more than 2 years.
Now as for dexcool sludge/foam/mud, the best cure for that seems to be
this. KEEP air out of your system, Keep your radiator cap clean, Keep
your overflow bottle filled to the highest mark, and use only distilled
water with 50/50 mixes. Those 4 things I found seem to help out a lot.
Keep in mind that just because a cooling system says 5 years 150k miles
doesnt mean you can ignore checking the system that long! Check it
weekly and monitor for any coolant loss and if there is any find where
its going and fix it. If you cant find GM dexcool the best alternatives
are silicon phosphate free coolants. Avoid putting anything in the
system containing those 2 things. Prestone and Havoline both make
coolants that are compatible with dexcool but arent exactly dexcool. GM
only mentions Havoline as having a coolant compatible with dexcool. So
if you in a bind or you dont want to buy dexcool try those out.
One more note to add, I think if you have both types mixed in a cooling
system the corrosion inhibitors attack eachother shorting the life of
the coolant much sooner than 2 years. So keep that in mind.

Post by Dick

Post by Robertwgross

Post by GMdude
When it comes to colors/dyes. When you mix orange with green, you get
brown.

NO JOKE!
That wasn't the issue. I think you missed my point. The question was what was
going on when you mix clear, orange Dex-Cool with clear, green normal coolant,
and shortly later you get this frothy mess. If it were clear and brown, that
would not be too surprising.
---Bob Gross---

The brown stuff has nothing to do with mixing in other coolant. It is
an issue with the Dex-Cool and has happened in several instances. The
main cause seems to be running too low on coolant.
You did not say what year that car was. There were problems with some
of the 1999 models. Perhaps some materials used in the engine were not
compatible with the coolant but GM has denied any connection. In all
cases they say that proper maintenance was the issue.
Problems seem to be especially bad with Dex-Cool when the owner lets the
level get too low or top off with water instead of a coolant mixture.
Some brown stuff that has been seen comes from leak preventatives.
It is important that you have Dex-Cool you should make certain the
over-flow tank is full at all times. Of course that is important with
all coolant but especially with Dex-Cool.

[Robertwgross]

Post by Bon·ne·ville
From what "I've experienced" and have seen the conventional green
coolant attacts aluminum towards the end of its life cycle vigorously.
I've seen some pretty bad pitting on machined mating surfaces of
aluminum. I've also seen hardened clusters of silicon bonded to aluminum
surfaces. The silicon contained in green coolant isnt the healthiest
stuff you can put in a modern cooling system. As the coolant ages the
silicon tends to bond to each other forming larger particals and it
begins to eat away at aluminum like a sand blaster. The aluminum pipes
on heater cores seem to often fail because of this. (my theory)
When ever you put a silicon based coolant in your cooling system you
must and I mean MUST change your coolant every 2 years. Even if you try
to switch back to dexcool. I can look at a system that has had green
coolant in it and it is coated with scaling even from short term use.
That coating "prevents" dexcool corrosion inhibitors from effectively
lasting more than 2 years.
Now as for dexcool sludge/foam/mud, the best cure for that seems to be
this. KEEP air out of your system, Keep your radiator cap clean, Keep
your overflow bottle filled to the highest mark, and use only distilled
water with 50/50 mixes. Those 4 things I found seem to help out a lot.
Keep in mind that just because a cooling system says 5 years 150k miles
doesnt mean you can ignore checking the system that long! Check it
weekly and monitor for any coolant loss and if there is any find where
its going and fix it. If you cant find GM dexcool the best alternatives
are silicon phosphate free coolants. Avoid putting anything in the
system containing those 2 things. Prestone and Havoline both make
coolants that are compatible with dexcool but arent exactly dexcool. GM
only mentions Havoline as having a coolant compatible with dexcool. So
if you in a bind or you dont want to buy dexcool try those out.
One more note to add, I think if you have both types mixed in a cooling
system the corrosion inhibitors attack eachother shorting the life of
the coolant much sooner than 2 years. So keep that in mind.

Surely you are referring to silicates, not elemental silicon.

---Bob Gross---

[Bon·ne·ville]

Post by Robertwgross

Post by Bon·ne·ville
From what "I've experienced" and have seen the conventional green
coolant attacts aluminum towards the end of its life cycle vigorously.
I've seen some pretty bad pitting on machined mating surfaces of
aluminum. I've also seen hardened clusters of silicon bonded to aluminum
surfaces. The silicon contained in green coolant isnt the healthiest
stuff you can put in a modern cooling system. As the coolant ages the
silicon tends to bond to each other forming larger particals and it
begins to eat away at aluminum like a sand blaster. The aluminum pipes
on heater cores seem to often fail because of this. (my theory)
When ever you put a silicon based coolant in your cooling system you
must and I mean MUST change your coolant every 2 years. Even if you try
to switch back to dexcool. I can look at a system that has had green
coolant in it and it is coated with scaling even from short term use.
That coating "prevents" dexcool corrosion inhibitors from effectively
lasting more than 2 years.
Now as for dexcool sludge/foam/mud, the best cure for that seems to be
this. KEEP air out of your system, Keep your radiator cap clean, Keep
your overflow bottle filled to the highest mark, and use only distilled
water with 50/50 mixes. Those 4 things I found seem to help out a lot.
Keep in mind that just because a cooling system says 5 years 150k miles
doesnt mean you can ignore checking the system that long! Check it
weekly and monitor for any coolant loss and if there is any find where
its going and fix it. If you cant find GM dexcool the best alternatives
are silicon phosphate free coolants. Avoid putting anything in the
system containing those 2 things. Prestone and Havoline both make
coolants that are compatible with dexcool but arent exactly dexcool. GM
only mentions Havoline as having a coolant compatible with dexcool. So
if you in a bind or you dont want to buy dexcool try those out.
One more note to add, I think if you have both types mixed in a cooling
system the corrosion inhibitors attack eachother shorting the life of
the coolant much sooner than 2 years. So keep that in mind.

Surely you are referring to silicates, not elemental silicon.
---Bob Gross---

Silicate would of probably been more correct if not more correct
sounding but its basically all the same in the end. Silica, silicate,
silicon if its not the same then whichever form of it if they put in the
green coolant will eat aluminum up. Silicate crystals can clump together
and do a number on the system through erosion. Iron can handle it just
fine but aluminum which is found more and more doesnt like it very well.
Thats one reason for so many new coolants out on the market now. Anyhow
the whole green coolant/dexcool coolant debate has been going on for a
long time...and so will this thread most likely.

http://dictionary.reference.com/search?q=silicate

[Robertwgross]

I was thinking that pure silicate-based coolants do not corrode the aluminum
system if everything is clean, but over a period of time, combustion byproducts
and other *crappy* acids get into the coolant. That acidic blend is what makes
coolants go bad, and that is why coolants are recommended to be replaced
periodically. However, that is my thought, and I don't fully understand the
detailed chemistry going on in there.

---Bob Gross---

[chuck]

Post by Dick

Post by Robertwgross

Post by GMdude
When it comes to colors/dyes. When you mix orange with green, you get
brown.

NO JOKE!
That wasn't the issue. I think you missed my point. The question was what was
going on when you mix clear, orange Dex-Cool with clear, green normal coolant,
and shortly later you get this frothy mess. If it were clear and brown, that
would not be too surprising.
---Bob Gross---

The brown stuff has nothing to do with mixing in other coolant. It is
an issue with the Dex-Cool and has happened in several instances. The
main cause seems to be running too low on coolant.
You did not say what year that car was. There were problems with some
of the 1999 models. Perhaps some materials used in the engine were not
compatible with the coolant but GM has denied any connection. In all
cases they say that proper maintenance was the issue.
Problems seem to be especially bad with Dex-Cool when the owner lets the
level get too low or top off with water instead of a coolant mixture.
Some brown stuff that has been seen comes from leak preventatives.
It is important that you have Dex-Cool you should make certain the
over-flow tank is full at all times. Of course that is important with
all coolant but especially with Dex-Cool.

I read an artical in motortrend that said the new coolant has an acid
in it for aluminum radiators and if you use it on older ones it will
eat up the solder joints over time---they didn't say how long or what
concentration--probably 100%--I haven't seen anything from gm on this
though----

[Marky]

There is an awful mess of (mis)information surrounding this issue. I
have read technical information from the proper sources that do say there
is no problem inherent to mixing Dex and green (other than decreased
expected life). I have, however, seen to many instances of brown cottage
cheese in vehicles that were running mixes. Some sources indicate that
this is coincidental, and actually due in part to faulty/improper radiator
caps. This is one issue, however, that I personally would just not be
comfortable accepting manufacturer's information. It's just my own
peace of mind (for my own cars and in respect to comebacks) to never mix.

Post by GMdude
Vito,
Mixing Dex-Cool and green coolant is not recommended by GM. But the
green coolant can be added, when you are in a bind, and you don't have
Dex-Cool. It will not harm the engine, gel, or gum-up, as Bob has
stated. It will however reduce the life of the coolant, to that of the
green coolant.
When you have your mechanic repair the leak, have him flush the cooling
system well, and re-install the Dex-Cool. No chemical flushing is
needed, or advised. Both coolants are of an ethylene glycol base.
Dex-Cool has a longer life, and is better for the environment.
I received the above information, from an instructor at the GM training
facility, in Hinsdale, IL, while taking a course. His information came
from an engineer in Detroit.
This myth of gelling-up, or gumming-up, is just that. A myth.
GMdude

[Phillip Schmid]

Post by Marky
There is an awful mess of (mis)information surrounding this issue. I
have read technical information from the proper sources that do say there
is no problem inherent to mixing Dex and green (other than decreased
expected life). I have, however, seen to many instances of brown cottage
cheese in vehicles that were running mixes. Some sources indicate that
this is coincidental, and actually due in part to faulty/improper radiator
caps. This is one issue, however, that I personally would just not be
comfortable accepting manufacturer's information. It's just my own
peace of mind (for my own cars and in respect to comebacks) to never mix.

I agree. My uncle is a manager of a garage around here and he says that
every now and then someone comes in wanting a coolant flush/refill and he
said something about putting dex-cool and antifreeze together in one
container for the waste people to get rid of. But at the bottom of this
container there was hardened stuff that he needed to chip away and since
then they've been using 2 containers, the problem hasn't happened since.

[Marky]

Yeah. I'm kinda starting to think that while there may not be a problem
mixing fresh green and fresh Dex, perhaps adding one or the other to an
established cooling system that has suffered the routine contaminate
buildup and additive depletion is where we get in trouble. (Like there's
no problem until electrolysis set in?) I am not a chemist, so I'm just
speculating, of course.

Post by Phillip Schmid

Post by Marky
There is an awful mess of (mis)information surrounding this issue. I
have read technical information from the proper sources that do say
there is no problem inherent to mixing Dex and green (other than
decreased expected life). I have, however, seen to many instances of
brown cottage cheese in vehicles that were running mixes. Some sources
indicate that this is coincidental, and actually due in part to
faulty/improper radiator caps. This is one issue, however, that I
personally would just not be comfortable accepting manufacturer's
information. It's just my own peace of mind (for my own cars and in
respect to comebacks) to never mix.

I agree. My uncle is a manager of a garage around here and he says that
every now and then someone comes in wanting a coolant flush/refill and
he said something about putting dex-cool and antifreeze together in one
container for the waste people to get rid of. But at the bottom of this
container there was hardened stuff that he needed to chip away and since
then they've been using 2 containers, the problem hasn't happened since.

[Rich B]

Mixing Dexcool and regular antifreeze is not recommended by GM or the
people that manufacture Dexcool. Dexcool has a bad reaction to any
contaminant and that list includes air, dirt and green antifreeze. Many
of the problems with Dexcool have been traced to faulty radiator caps
and incomplete "burping" of the sytem at the factory to remore trapped
air.

[Isaiah Beard]

Post by Vito Cavallo
I has the orange Dexron coolant.

Dex-cool, you mean. Dexron III is transmission fluid. :)

Post by Vito Cavallo
The car was not blowing heated air, so I
checked the radiator. The coolant level was very low, so I put in some
green Texaco coolant.
Can I mix Dexron and regular antifreeze, or will I blow my engine?

Flush it out as soon as you can. Mixing the two means you run the risk
of turning your coolant into a brown slush that doesn't do its job well
at all.

Post by Vito Cavallo
The car is in the repair shop for the coolant leak, but I want to know for
the future.

No, don't mix the two. Pick one or the other, and stick to it. And if
you choose the green stuff, make sure he cooling system is thoroughly
flushed out before you fill it.