Dexron Antifreeze mixing

(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---

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

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---

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

Bob,

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

GMdude

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---

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 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.

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.

In article , snipped-for-privacy@noplace.net says...

Surely you are referring to silicates, not elemental silicon.

---Bob Gross---

Silicate would of probably been more correct if not more correct=20 sounding but its basically all the same in the end. Silica, silicate,=20 silicon if its not the same then whichever form of it if they put in the=20 green coolant will eat aluminum up. Silicate crystals can clump together=20 and do a number on the system through erosion. Iron can handle it just=20 fine but aluminum which is found more and more doesnt like it very well.=20 Thats one reason for so many new coolants out on the market now. Anyhow=20 the whole green coolant/dexcool coolant debate has been going on for a=20 long time...and so will this thread most likely.

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---

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----

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.

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.

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

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.

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.