Hey guys, ive been in the market to purchase a Cobalt as of late, certified preowned or new im not sure yet. My first car i ever owned was a 1995 cavalier z24 and i was a big fan, my account is still over on jbody.org actually.

Anyhow, back when i owned my cavalier, it had dexcool in it, and like all cars with dexcool, it had a bad case of dexcool rot, which i had no idea what that was at the time....



on the cavalier, it would blow headgaskets, on monte carlos, and other GM's it would rot the intake manifold gaskets. My question to you is, have you folks been expieriencing similar issues like this with your cobalts, what parts does it effect first, and what do you folks do for prevention?

 

wow that is f**king bad

 

yeh, and the dexcool just caused the intake manifold gaskets to blow on my friends monte carlo last week, so its a big concern for me when buying the car

 

i work at a dealer and personally i've never seen or heard of dexcool causing an issue like that yet? from that pic how old was the car when that happened?

 

Probably said 95 Cavalier with original coolant.

 

that pic is from a newer car on the bonneville forum, ive seen that happen on my cousins new truck, and i had similar symptoms of that on my cavalier back when i had it, although not nearly severe

 

From what I remember reading, Dexcool was an issue in some early designs as all of the air was never purged out of the radiator & cooling system and it caused excessive corrosion as you have shown above.

It's been a few years since I have read of it so I've probably F'ed up the details.

I can say that my now 6+ year old Trans Am WS6 on Dexcool has no corrosion showing at all.
I purchased it in 2005 and flushed the system last year & refilled it with new Dexcool at 70%.

This year I drained a gallon and replaced it with a 70% mix. I plan to do this each year to keep the corrosion inhibitors strong.

 

ya the reason i'm asking is i've worked on some cars that are poorly maintained and have never had that. now granted thats only a minimal portion of the gm vehicles out there. but after about 5 years dexcool does breakdown and starts to look like that which is why i was asking about how old vehicle in the pic was.

 

yeh i didnt see to much in the way of problems with dexcool on the forum

so not much in the way of problems regarding headgaskets or coolant leaks from corrosion on the balts i take it?

 

Dexcool (low silicate) coolant is fine and has good properties. Our dealership (at the time), did not agree with the extended flush/replace intervals advertised. Instead of the 5 year-150,000 mile interval, we tried to aim for the vicinity of 3 year-75,000 mile flush/fill and served our customers a lot better in the long run.

GTO 1

 

so what do you say about the known problems with dexcool and the class action lawsuit that was filed against GM regarding it?

 

Is that the one about the intake manifold gaskets? That's one thing our engines have as an advantage; the coolant never passes through the intake manifold so one big source of trouble is eleminated.

I've always wondered if a lot of the trouble people have with Dexcool (the rusty sludge buildup, etc) is due to improper bleeding and purging of the air in the system during flushes and fills. The old fashioned green coolant worked fine even if there was a lot of air in the system, but not Dexcool apparently. And some cars are notoriously sensitive to how the air is purged from the system so it just makes things worse. Anyway, that's my theorey.

 

well good to know that they didnt do anything retarded with the ecotec engine and i wont have to worry about the intake manifold gasket

 

To give you further confidence - I've never heard of anyone here or on RLF having dexcool coagulation. The worst I've seen is an oil cooler cracked and bled oil into the coolant system, but I've only seen that once on forums.

But holy hell, seeing all the complaints about Dexcool makes me want to flush and refill with regular stuff. >_>
http://www.consumeraffairs.com/autom...m_dexcool.html

It also seems that none of the complaints were from vehicles past 2002ish. Anyone know if there was a gasket material or Dexcool formula change?

 

The thing with cooling systems these days is people think that just because it says the coolant will last 5yrs/150k miles, they don't have to maintain it. As long as you properly maintain your cooling system, you usually have nothing to worry about.

A side note on the V6 & V8 intake problems. They used to use a "plastic" gasket material. GM redesigned the gaskets recently (past 2 years or so) and it is now metal, so they don't break apart around the intake manifold/head coolant ports. And yes, bleeding ALL the air is a very necessary thing with dexcool. Thats why I use a venturi vacuum every time I make a repair. Just some FYI.

Also, a lot of the time, the sludge is caused by mixing dexcool with the old green coolant. Makes a very thick, hard to remove sludge that cloggs passages and eventually hardens. I've had to literally chip out coolant ports on intake manifolds to clear them.

 

Just a bit of info that might help some ppl out........dexcool is great coolant as long as it does not come in contact with air and aluminum at the same time.......this causes very bad things to happen......and since most of the vehicles are aluminum heads, intakes,rads and whatnot its very important to keep the coolant system maintained.......On the other hand there is absolutly no problem if you switch to universal green coolant in a gm vehicle as long as the system is very well flushed........a lot of people will argue this but thats their problem......i have always switched my dexcool for green universal and never ever had a problem and so have a lot of people......It has to be replaced more often but its a lot cheaper in the end than having to replace an intake or a rad because there was a small leak that created a bigger problem.....Just my 2 cents.....Later

 

dexacool is garbage it ate my gtp intake manifold gasket ($500) get that crap out!!

 

dexacool is fine but if you own a blazer the heater cores get eaten up fast so flush and put green in your safest bet

 

That would make Dexcool the opposite of fine in my book. >_>

 

Only problem in my family due to dexcool was the 3.1L V6 intake gasket leak(extremely common on 3.1/3.4s). No problem w/ my Camaro and it had 125k miles w/ dexcool in it.

 

My understanding of the dexcool problem is this: When GM originally changed to dexcool it was unknown that the coolant was "eating" the gaskets. Once the gaskets began leaking and air became trapped in the coolant system, the dexcool began to cause corrosive damage to the aluminum intake manifolds.

GM has changed the gasket material which has caused the dexcool problem to pretty much go away. There was an incident in the last 2 or 3 years where a bad batch of gaskets for the V6 motors caused this issue to resurface, but other than that there have been few dexcool problems.

If you mix dexcool with green ethylene glycol it wil turn into the muddy orange goop as seen in the picture:



People take their cars to instant oil change places and into shops for maintenance all the time, and it does happen that some tech can put the wrong antifreeze into the car. Even the "universal" antifreeze that should be safe I don't know if I would trust it.

Also, I personally dont' trust the 5 year/150K lifespan. I typically change the coolant every 2 or 3 years.