Why Dex Cool?

[allenGP]

Is it completly nessecary to use dex cool?

I got my 2000 GP a few years ago and when i went to flush the radiator it was all rusty colored, i think they had the green stuff in it.

When i refilled I used the green stuff wasnt aware the car is supposed to run Dex cool.

Already 6 months later its rusty looking again. so I flushed it and put dex cool in it. Now im reading all these bad stories about dex cool...

Do we have to use it?

Was the green fluid likely the culprit making my fluid turn brown?

 

I just want to know what I should use and why my fluid is turning brown. Thanks in advance.

[Heartbeat1991]

I use it. If you used Dex-cool and you mixed it with tap water, that will negate the benefits of the Dex-cool. The fluid is turning brown from rust. If it's brown again, you need to flush again. Use a flushing agent.

[allenGP]

so mix it with distilled water?

[carkhz316]

Eh, while distilled is optimal, tap water is ok for Dex-cool. The problem lies in exposure to air, due to leaks and whatnot that cause air to be introduced to the system. The oxygen in the air trapped in the system is what can/ will cause oxidation and other gunk to build up.

[94 olds vert]

I have dex cool in my 14 year old GTP and it is still working just fine.

[White93z34]

I always run what the manufacturer recommends.

 

You could run whatever you please for the most part just keep in mind that

 

a) you need ONLY use your coolant of choice, flush out all of the old coolant before switching

sometimes when switching to different coolants waterpumps tend to fail.

[Heartbeat1991]

Tap water introduces minerals that negate the corrosion resistance. Distilled is the correct way to do it. If you're going to use tap water, you might as well throw green stuff in there.

[allenGP]

ok thanks a ton everyone. Ill probably have to flush it again soon sounds like

[Schurkey]

Eh, while distilled is optimal, tap water is ok for Dex-cool. The problem lies in exposure to air, due to leaks and whatnot that cause air to be introduced to the system. The oxygen in the air trapped in the system is what can/ will cause oxidation and other gunk to build up.

So why is the coolant in the overflow bottle, which is exposed to air constantly, not usually a problem?

 

I'm not buying the oxygen-sensitivity with Dexcool. Oil or fuel sensitivity, maybe. Intake gasket fails, or a casting cracks, and there used to be problems with Dexcool gelling. Far as I know, that hasn't been a problem for years.

 

ok thanks a ton everyone. Ill probably have to flush it again soon sounds like

HOW are you draining the flush water? If you're not pulling the block drains, you're going to leave a lot of crap in the block. That crap then contaminates the fresh coolant.

 

This is made more difficult since some engines don't have block drains. Buick small-blocks and V-6 come instantly to mind--seems like some do, some don't.

 

 

 

 

 

There's plenty of other brands of extended-life coolant. You don't like Dex-cool, you could select another brand, or use non-extended-life coolant.

Edited November 6, 2014 by Schurkey

[GnatGoSplat]

I've never had any problems with Dex-cool. It stays bright orangish red and always looks clean in my truck. I also switched to it in my 89 Cutlass in the late 90s when I completely flushed the cooling system and it's been fine with no discoloration.

 

On the other hand, my mother-in-law has a hideous boxy Malibu, can't remember the year. Might be an 05, not sure, but that body style with a 3400. Its coolant looks like used motor oil and was sludgy. It wasn't oily, so there was no oil mixed in. No clue why it looks like that. I heard GM used to put pellets in the cooling system that may have been responsible for that appearance.

 

Maybe if you flush it out completely, the coolant will stay bright red/orange.

[carkhz316]

So why is the coolant in the overflow bottle, which is exposed to air constantly, not usually a problem?

 

I'm not buying the oxygen-sensitivity with Dexcool. Oil or fuel sensitivity, maybe. Intake gasket fails, or a casting cracks, and there used to be problems with Dexcool gelling. Far as I know, that hasn't been a problem for years.

I admittedly paraphrased that from Wiki, so buy it or not, that's GM's reasoning behind the issues (or lack thereof) with Dexcool. I never explicitly stated it was reacting with the antifreeze itself: but implied the metals instead. As far as the open to atmosphere coolant bottles: I don't know. I'm guessing it's never a problem with being in a plastic container versus being in metal.

 

On a side note, you don't have to be so snarky and condescending in your posts all the time. While you're right pretty much most of the time, and seem like a really smart person, you could be a little nicer about it instead of belittling people.

[Heartbeat1991]

I admittedly paraphrased that from Wiki, so buy it or not, that's GM's reasoning behind the issues (or lack thereof) with Dexcool. I never explicitly stated it was reacting with the antifreeze itself: but implied the metals instead. As far as the open to atmosphere coolant bottles: I don't know. I'm guessing it's never a problem with being in a plastic container versus being in metal.

 

On a side note, you don't have to be so snarky and condescending in your posts all the time. While you're right pretty much most of the time, and seem like a really smart person, you could be a little nicer about it instead of belittling people.

 

?? I don't see anything snarky or belittling here. ??

[carkhz316]

?? I don't see anything snarky or belittling here. ??

Perhaps that is just my perception. It seems like there has been other times of this and not just here, and not directed at me either.

[Euro]

I took that shit out. Green coolant FTW

[Imp558]

Mine was nasty, went green and all is well for many years.

[Heartbeat1991]

I always use the DexCool. I see no point in changing it.

[Imp558]

This is made more difficult since some engines don't have block drains. Buick small-blocks and V-6 come instantly to mind--seems like some do, some don't.

 

 

3800 Knock sensors run into coolant passages on the SII Engines, it's possible to drain them there.

 

There's a class action lawsuit against GM over Dex-Cool, make what you will of it but a judge saw it necessary.

http://www.bigclassaction.com/lawsuit/dexcool_damage.php

 

Also, the OP may want to check the vehicle and ensure the Engine-Frame ground is good to eliminate any electrolysis.

[Schurkey]

I took that shit out. Green coolant FTW

I always use the DexCool. I see no point in changing it.

There's a class action lawsuit against GM over Dex-Cool, make what you will of it but a judge saw it necessary.

http://www.bigclassaction.com/lawsuit/dexcool_damage.php

To Dex, or not to Dex, that is the question.

GM has bulletin(s) on Dexcool causing problems, gelling, etc. No question there were problems with the coolant, the gaskets, and some sort of chemical interaction that was not desired.

 

That said, GM is still using "Dexcool"; and they're doing it successfully in millions upon millions of vehicles. There's nothing inherently wrong with Dexcool as currently produced. I maybe wouldn't say that about Dexcool as produced in the first couple of years--I have the feeling it was "updated" when there were enough problems to cause the bulletins to be issued.

 

AGAIN, even if you're allergic to Dexcool--and I don't think there's a reason for that anymore--there are multiple other brands of extended-life coolant. Green is not the only option.

 

3800 Knock sensors run into coolant passages on the SII Engines, it's possible to drain them there.

Yup. Common on certain engines to thread the knock sensor into a block drain hole. But there are some engines that just plain don't have a block drain hole because GM wanted to save another five cents.

 

Also, the OP may want to check the vehicle and ensure the Engine-Frame ground is good to eliminate any electrolysis.

Always a good idea to verify radiator (coolant) voltage is appropriately low. A simple test that is hardly-ever performed. Sometimes the voltage is from a poor ground, so the coolant becomes the ground; other times the dis-similar metals in the cooling system along with worn-out coolant that acts as an electrolyte creates a "battery" that produces voltage and corrosion.

 

 

 

 

 

 

 

P.S. Notice my signature line: I have an obligation to my fans to be snarky.

[GnatGoSplat]

Always a good idea to verify radiator (coolant) voltage is appropriately low. A simple test that is hardly-ever performed. Sometimes the voltage is from a poor ground, so the coolant becomes the ground; other times the dis-similar metals in the cooling system along with worn-out coolant that acts as an electrolyte creates a "battery" that produces voltage and corrosion.

 

How is that done? Negative lead on chassis and positive lead on radiator, check to see how close to 0-volts? Could that account for why I can't get any coolant level sensors to not light up the "Low Coolant" light? Of course, that could just be all 3 used ones I got and one new aftermarket are all crap. Haven't tried a new OEM one yet.

[Schurkey]

http://www.rondavisradiators.com/tech.htm (scroll down)

 

http://www.sancarlosradiator.com/VoltageDrop/

[Heartbeat1991]

That class action case was 10 years ago.

[Imp558]

I guess the way I rationalize not running it is this:

People will take small precautions every day, maybe a different route home from work to avoid a rough neighborhood? Sure there may only be a small chance of getting mugged or carjacked or whatever but it still makes sense to most people.

So if there have been problems in the distant past, even if they changed the composition to fix it the safe route is still to run another coolant that has never had an issue.

Likely the OP could thoroughly flush the system, eliminate any questions about electrolosys and run new Dex without ever having a problem. But running green or using other extended life coolant as Shurkey suggested is just as easy and eliminates any issues.

[Human]

There is extensive information on the pontiacbonnevilleclub.com forum regarding DexCool. Many blame it for the intake manifold gasket failures common to 3800 Series II engines. You actually can run either Dex or non-Dex in the engine, just don't mix them, as that will turn turn your coolant to sludge. The anti-Dex people over on the Bonneville board suggest thoroughly flushing out the cooling system and using the "Mixes with Anything" coolant instead of Dex.

[Nas Escobar]

There is extensive information on the pontiacbonnevilleclub.com forum regarding DexCool. Many blame it for the intake manifold gasket failures common to 3800 Series II engines. You actually can run either Dex or non-Dex in the engine, just don't mix them, as that will turn turn your coolant to sludge. The anti-Dex people over on the Bonneville board suggest thoroughly flushing out the cooling system and using the "Mixes with Anything" coolant instead of Dex.

 

Some have said that you can run the green with dex so long it's "safe to mix". I personally wouldn't do such a thing and tell people to flush out the whole coolant if they mixed for precaution's sake HOWEVER that is now considered the "old school" of thought as the formula for dex has changed since that class action lawsuit. Dexcool is still not water friendly, and THAT will cause sludge as well. I personally would revert to green. It's just easier to deal with. Yes you have to flush it out more often but it's also a lot easier to find Prestone 50/50 mix than GM backed Dex.

 

On an interesting note, I've seen some import drivers use Dex on their engines. While this is mostly a Nissan and VW thing, it's still something rather strange.

 

I personally say in this topic, use what you feel comfortable with. Yes Dex has its issues but so does the green stuff and the orange stuff that Toyota uses, and any other color you can come up with. Most of these companies nowadays have their own "color" coolant. I think there's around 5 colors in todays world.

[Schurkey]

Dexcool is still not water friendly, and THAT will cause sludge as well.

Huh?