Sorry Dex Cool haters

[antiqueshell]

I agree that with pressurized correctly functioning cooling systems there is not a problem.

My guess is that since Dexcool was introduced slight tweaks in the chemistry have also eliminated previous issues with unpressurized systems.

 

[cchase]

The cooling system on my GTO doesn't even have a pressurized overflow. I haven't noticed any sludge yet.

 

[LeakySeals]

My DEX-DEATH nightmare continues! Been going on since 69k. I've never experienced anything like this on any car I've ever owned. I keep draining and filling the radiator, cleaning the expansion tank every couple of months, but its always the same. After I pour out the coolant in the tank there is a layer of DEATH SLUDGE stuck to the bottom of the tank. Have to go to the sink and pressure spray it out.

Clean again for the 15'th time.

Between this and the oil consumption I'm sick of GM after only 6 months. Been with Toyotas for a few years, nothing like this. Regretting giving GM one last try. This car will never make it as far as the old Camry. Maybe a Ford next time. But thats it, will stay with the Asians for now on.

 

[hisilver]

Are you using RMI-25? I don't use or know much about the stuff but could that be the harmless 'gel' they say forms?

 

[mechanicx]

I wouldn't write the Grand Prix's durability off just yet over a little bit of sediment in the reservoir. Those 3.8's are known to run a long time. Some sediments usually is not harmful to the cooling system if it is not excessive. Although I agree the sediment is annoying and that Dexcool doesn't work well with the non-pressurized reservoir on that application. The Grand Prix was an older platform that not everything got fully updated on. Ford is going to Dexcool.

With Dexcool the particles tend to float to the top and not to the bottom like some coolants. Your cooling system itself is probably pretty clean. If the sludge bothers you, you could switch out the coolant to a non-OAT formula or to a HOAT formula. Original green works well but has silicates and has to be changed more often. Some people run G-05 but I don't like it much and it has silicates. You could use a HOAT like Toyota SLL coolant or Ford Speciality Green concentrate, and the phosphates might prevent rust from forming in the reservoir. You can run any of those coolants you want if you do a complete change out.

If you do want to stay with Dexcool, you might consider replacing the radiator cap just in case, and use a licensed Dexcool. I prefer Havoline or GM vehicle care brand (GM dealer Havoline) but not ACDelco brand (Prestone), or maybe Zerex. Mixed at 50-55% of course and perferably distilled water. I'm not sure what Dexcool you are using now, allmakes, Prestone premix or what. And make sure the radiator is full and fill the reservoir all the way to the hot mark. I assume the cooling system is leak free. But yeah, those W-bodies seem prone to have sediment with Dexcool. Maybe it's a combination of a low radiator, non-pressurized reservoir that's too small, and iron heads. Dexcool works flawlessly in many other GM models.

 

[pbm]

Mechanicx:
Are you saying that you do or don't care for the Prestone Dexcool? I picked up a bottle for top-up in my Chevy Cruze which loses a bit of coolant from the tank over a few months.

What is it that you don't like about G-05?

 

[mechanicx]

There's nothing wrong with Prestone Dexcool per se. I've seen anecdotal evidence that it might not be as sludge resistant on problem cars, but on other late models Prestone works fine. It's just that Havoline Dexcool uses sebacic acid as the secondary OAT inhibitor and that inhibitor seems to be held in high esteem and used by various OE coolants. And Zerex I believe uses molybdate so in a sense their Dexcool is somewhat of a HOAT. It's not a big difference but I prefer Havoline given a choice.

I don't like G-05 as substitute for Dexcool for minor reasons, and don't see much benefit over green. I don't like that at least the non-Chrysler brand is not really dyed, also as all makes aren't. It leaves a powdery residue where ever it over flows out of the system. It uses borates and nitrites, which some automakers disfavor for aluminum protection, then you have the silicates concern. G-05 is not as available as Dexcool or probably green. But G-05 does offer good corrosion protection.

I'm not really a fan of Peak Global either.

I like to always use the OE formula. I think Dexcool is a great coolant, except for the issue that shows up on some situations. For example, if I were not to use the OE coolant on say a Toyota that I knew is leak free and coolant levels will be maintained, I would use Dexcool over G-05 or Green.

 

[cchase]

Originally Posted By: LeakySeals

Between this and the oil consumption I'm sick of GM after only 6 months. Been with Toyotas for a few years, nothing like this. Regretting giving GM one last try. This car will never make it as far as the old Camry. Maybe a Ford next time. But thats it, will stay with the Asians for now on.


I'm wondering - did you buy this car new? If not, do you know what kind of cooling system maintenance it has had since new? I'm suspecting the answers to both those questions are "no" based on your "6 month" comment. So how are you to assume that the issue is Dexcool, or GM, or your car, and not some kind of prior neglect (or mixing coolant types) that you are now flushing out with your frequent coolant changes? After all, draining and filling isn't nearly as effective or complete as draining the system entirely and flushing with water. Realistically most of my drain/fills seem to get 1/5 to 1/4 of total volume out. I have no idea how long it would take to completely exchange fluid by doing that if I had sludge to begin with.

I'm not intending to "call you out", but I don't like 2nd, 3rd owner anecdotal evidence to be used as data. I'm also not trying to defend Dexcool or GM particularly, I just like to have all the facts before doing coming to a conclusion about a particular story.

 

[mechanicx]

Good point and not to call anyone out either but LeakySeals didn't really give enough info to really determine what's really going on or what's to blame.

While I maintain that Dexcool is more sensitive to low coolant levels than some other formulas are, I still think it is a great coolant that has a lot of pluses.

 

[LeakySeals]

Originally Posted By: mechanicx
Good point and not to call anyone out either but LeakySeals didn't really give enough info to really determine what's really going on or what's to blame.

While I maintain that Dexcool is more sensitive to low coolant levels than some other formulas are, I still think it is a great coolant that has a lot of pluses.

Bought the car used at 69k. The dex sludge existed at that time. Whether or not it was changed prior to that is doubtful based on condition. For OAT coolant to be in such poor condition at 69k its bad design, lousy fluid, or both. I've changed Toyota coolant for the first time with 150k on it and not seen anything other than the color being slightly off.

 

[LeakySeals]

Originally Posted By: hisilver
Are you using RMI-25? I don't use or know much about the stuff but could that be the harmless 'gel' they say forms?

Not at the moment. I was using it to help expedite the process. Then I decided to stop and see if it got any better. It doesn't the sludge keeps oozing out of it every couple of weeks. I keep draining and filling the expansion tank every 2 weeks. 1/2" of sludge every time. Horrible, will overheat this summer for sure if I cant resolve this. Thinking about replacing the radiator. Its like new but i cant stand looking at the stuff, need to take drastic measures.

That picture is not coolant, its 1/2" of sludge clinging to the tank after the coolant is poured out. I have to blast it in the sink to get it out. Wont just pour out.

 

[LeakySeals]

Its too bad because I really love the way it handles, the smooth quiet idle and power of the engine. Its a joy to drive compared to the old 4 banger Camry.

 

[mechanicx]

Originally Posted By: LeakySeals
Originally Posted By: mechanicx
Good point and not to call anyone out either but LeakySeals didn't really give enough info to really determine what's really going on or what's to blame.

While I maintain that Dexcool is more sensitive to low coolant levels than some other formulas are, I still think it is a great coolant that has a lot of pluses.

Bought the car used at 69k. The dex sludge existed at that time. Whether or not it was changed prior to that is doubtful based on condition. For OAT coolant to be in such poor condition at 69k its bad design, lousy fluid, or both. I've changed Toyota coolant for the first time with 150k on it and not seen anything other than the color being slightly off.


Yeah but over 69k miles and time, the coolant could've been ran low and not topped up, just water was added, or who knows, and this maybe is old rust being beachheaded off. I'm not entirely disagreeing with you that the cooling system setup on these models doesn't keep the coolant totally clear. But as I suggested, unless you have 50-55% quality licensed Dexcool like Havoline or Zerex coolant mixed with perferably distilled water, it's hard to say what's going on. If after that you still have the problem and it bothers you, you could switch to another type of coolant.

Like you said Grand Prixs are nice in a lot of other ways. They're pretty reliable/durable too. Overall, I think they are a good value.

Oh yeah you were using RMI-25. It could possibly be that's what leaving the deposits in the reservoir. Usually if dexcool is causing sludge it leaves a reddish/brown film at the radiator cap and also in the reservoir. I'm not really sure if the percipitants you're seeing in the reservior are the same thing.

 

[LeakySeals]

Yeah it was on the cap too like you said. At the time of the pic there may have been a small amount of RMI-25 from prior drains left in the system, but that was 2 drains ago so its a small amount. I don't understand where is coming from at this point. I'm on the 5th drain and fill of PGL 50/50 distilled, 2 had a quart of RMI-25. In less than 10k I've owned it. Thats a lot of coolant passing through. The dex should be entirely eradicated. But it continues to "bloom". One more next week, hopefully that will be the end of it.

Unless PGL's no good and making it worse???

I usually stick to the factory fills for coolant and tranny. Hope I'm not paying for making a switch!

 

[mechanicx]

So you're not even using Dexcool and have been using Peak Global Life, and RMI-25? What did the coolant look like and the level when you first got the car? I don't really think much of PGL. You're not even using Dexcool and no additives like is recommended, so it's hard to say what's going on or to blame Dexcool or GM's cooling design.

 

[SteveSRT8]

Originally Posted By: mechanicx
So you're not even using Dexcool and have been using Peak Global Life, and RMI-25? What did the coolant look like and the level when you first got the car? I don't really think much of PGL. You're not even using Dexcool and no additives like is recommended, so it's hard to say what's going on or to blame Dexcool or GM's cooling design.


Aah, now we know the whole story here. Another story blaming Dex but with significant leaps in the logic process.

I seriously doubt Dex is at fault here either, but with all the different things going on it would be impossible to get a "conviction".

 

[LeakySeals]

Originally Posted By: SteveSRT8
Originally Posted By: mechanicx
So you're not even using Dexcool and have been using Peak Global Life, and RMI-25? What did the coolant look like and the level when you first got the car? I don't really think much of PGL. You're not even using Dexcool and no additives like is recommended, so it's hard to say what's going on or to blame Dexcool or GM's cooling design.


Aah, now we know the whole story here. Another story blaming Dex but with significant leaps in the logic process.

I seriously doubt Dex is at fault here either, but with all the different things going on it would be impossible to get a "conviction".

I switched the PGL BECAUSE of the dex sludge problems. And I'm STILL experiencing problems with dex sludge. The sludge was there BEFORE PGL or RMI-25 when it was ALL DEXCOOL. Why i changed at all. would stay with factory spec if all was fine. but it wasn't, I had to do something. The pictures are remaining dexcool sludge. There is no missing part of the story. I made a change to fix a problem. Hope that helps clear the confusion.

 

[LeakySeals]

Originally Posted By: mechanicx
I don't really think much of PGL.

Why do you feel that way? Did you have a bad experience? I researched the issue, what people in my situation were using to resolve the problem. I'll do anything to resolve this, thanks for your help.

More: It was not low when purchased at 69k. I noticed sludge in the tank and on the cap in the first days checking things. According to records it had been at dealer on several occasions, once at 60k. i think the design of the expansion tank - lots of air introduced, at the full line the tank is 80% empty - exposes a weakness with this fluid, air. So I switched to a non 2-eha in hopes things would get better. Maybe in a sealed system with little or no air dex is fine. I'm guessing maybe a design compatibility because many have no issues.

 

[mechanicx]

Originally Posted By: SteveSRT8
Originally Posted By: mechanicx
So you're not even using Dexcool and have been using Peak Global Life, and RMI-25? What did the coolant look like and the level when you first got the car? I don't really think much of PGL. You're not even using Dexcool and no additives like is recommended, so it's hard to say what's going on or to blame Dexcool or GM's cooling design.


Aah, now we know the whole story here. Another story blaming Dex but with significant leaps in the logic process.

I seriously doubt Dex is at fault here either, but with all the different things going on it would be impossible to get a "conviction".


We didn't really have the whole story at least at this pint. I've seen enough cars that had sludge if ran at low levels. I've even owned a few since new and completely know the history and seen some issues when only FF and licensed Dexcool was used with the concentration verified with a refractometer. I'm not completely blaming Dexcool but I also know that Dexcool requires a system to remain completely full and some older models have some issues if even minor with Dexcool.

 

[mechanicx]

Originally Posted By: LeakySeals
Originally Posted By: mechanicx
I don't really think much of PGL.

Why do you feel that way? Did you have a bad experience? I researched the issue, what people in my situation were using to resolve the problem. I'll do anything to resolve this, thanks for your help.

More: It was not low when purchased at 69k. I noticed sludge in the tank and on the cap in the first days checking things. According to records it had been at dealer on several occasions, once at 60k. i think the design of the expansion tank - lots of air introduced, at the full line the tank is 80% empty - exposes a weakness with this fluid, air. So I switched to a non 2-eha in hopes things would get better. Maybe in a sealed system with little or no air dex is fine. I'm guessing maybe a design compatibility because many have no issues.


I'm not trying to knock PGL. True it doesn't contain 2-EHA but it is an OAT coolant and no OEM that I know of uses the formula. I have seen PGL do the same thing, leave sludge deposits, on applications that had a tendency to do it with Dexcool.

I also kind of doubt the reservoir/radiator keeps the engine completely full of coolant even though I think it siphons from the bottom of the reservoir. I think if you really want to fix the issue, you will need to go to original Green or maybe G-05 or one of the Asian coolants and maybe get a new OE cap. But you need to do a complete changover. I still think if the system was leak free and had the proper concentration of Dexcool Havoline or Zerex, distilled water, and is leak free and kept topped up that there wouldn't be any sludge.