My '97 Grand Prix GT with 49,000 miles recently had a water pump and thermostat fail. The dealer did a coolant flush and found severe black sludge (damn Dexcool coolant ). They were about to tell me that I would need a new radiator since the radiator wasn't reading properly even with a new thermostat and flush. The mechanic working on my car suddenly came over and told me it's finally reading properly after he repeatedly flushed the coolant.. he said all of the sudden heavy black sludge flushed from the coolant system and now the temperature is reading properly after repeat flushing.

The mechanic told me it may need to be flushed again several more times. I know the Dexcool caused this problem but here's my question to you guys. He tried hinting to me that the car is "running good for now" and seemed to imply this might have caused more unknown damage. I'm seriously considering selling the Grand Prix now. I've read reports online about similar problems causing blown head and/or intake manifold gaskets. Is it reasonable to believe the Dexcool sludge might have already caused severe damage to the engine or coolant system components (i.e. the radiator and heater core) and would you sell the car?

Anyway, I'm not someone who sits back and lets this kinda crap happen when Dexcool is a known problem. I'm sending the bill directly to GM with evidence from the dealer that this was caused by Dexcool. I won't be filing a class-action lawsuit like most consumers to get pennies back in return while the lawyers end up with all the monetary damages. If GM doesn't respond to my complaint with a reimbursement, I will take them to small claims court and will be reimbursed one way or another. I predict they won't even show for court and I'll receive a default judgement. Why won't they show??? Logic suggests if I win after they present a case.. the ruling will set court precedent and this will lead to thousands of future judgements against GM.

You get im tiger I do hope you get compensation,as much as i love these cars GM are not inclined to admit their flaws and failures.My father had a paint issue with his 91 blazer and got $0 compensation (he swares he'll never buy another GM) I know a lot of people have had dexcool problems so i think its time for GM to step up to the plate and do a recall and repair any damage done by dexcool.

MM 88k on one vehicle with dex and one with 72k no problems and both are 98s. That's the first time I heard of black sludge. Usually it's brown clumpy stuff. The part with the intakes were a cheap plastic that GM started using about the same time as dex since then they have changed the plastic that they use. The biggest problem with dex is too much water and too much air. If you keep it 50/50 and topped off and systems bled then you shouldn't have any problems.

just get rid or dexcool you can put the green stuff in at least thats what gm told me, now do we know if it is safe im not sure. im sure someone will be able to tell you. i changed mine and have had no problems, but who knows something might happend now i said something lol

Originally posted by HercMan:
f you keep it 50/50 and topped off and systems bled then you shouldn't have any problems.

Hi Hercman,

Actually, I know GM issued a technical service bulletin in 2000 stating the exact same thing. However, if this is so important.. why isn't its importance mentioned in the service manual and how can anyone be sure at all times that air pockets do not exist somewhere within the coolant system? The manual states that Dexcool is good for 150,000 miles or 5 years so that's called an 'implied warranty'. There is obviously a problem with Dexcool.. go to Google and search for "Dexcool sludge". There are literally several hundred complaints within the first few search page results.

I'm not one to sue and have the courts resolve my problems.. but right is right and wrong is wrong. I'll get reimbursed.. there isn't a doubt in my mind once I present my case with hundreds of similar testimonials. The court might even issue punitive damages since GM has been aware of these problems for sometime.

I don't know. I have almost 115,000 miles on my 98 GTP, and I've always been running Dexcool, and everything is fine. I've only flushed it once so far, and that was at 96,000 miles or so. I've never seen anything black in my cooling system. Only brown flakes by the radiator cap. But the flush was pretty clean.

Yea, I only found one other complaint online about "black" sludge. Keep in mind 99.9% percent of the sludge in my coolant system was a rusty looking brown until the last flush showed black sludge according to the dealership (it was flushed several times before showing black). I'm sure many people have black sludge too but it's not being completely flushed out since it took several attempts. There's no doubt a do-it-yourself garden hose flush wouldn't remove this stuff since even the machine didn't remove it after the first few flushes.

Btw, if any of you have Dexcool and your coolant has ANY sludge build up.. I would take it to the dealer now before it's too late. Btw, GM part #12346500 Prestone Heavy Duty Cooling System Cleaner is recommended to remove Dexcool sludge during a flush. Water and a garden hose won't do the job.. even the dealer didn't know about the part number above until I did some research online about Dexcool.

So does that mean my engine oil has an implied warranty for 3000 miles even if I take my car to the track every weekend and once in a while overtemp the engine? Not that I do but basically the same thing as the life expectancy of Dex. Put a little logic into this. If Dex was such a bad product then why does GM still continue to use it to this day? You think that if they had a quality issue that could be solved by simply changing coolant they would've done that already? And just how many vehicles have been produced that came from the factory with dex and just what is the percentage of those that actually have problems? Besides if anything GM would switch to the green since that stuff is cheaper to start with. So I'm not one of those anti dex people.

So does that mean my engine oil has an implied warranty for 3000 miles even if I take my car to the track every weekend and once in a while overtemp the engine?

You misunderstood my point and your analogy is flawed since you should expect the oil to last 3,000 miles.. under normal driving conditions according to the manual. Would you be a little pissed if your engine oil was caked after 3,000 miles and the subsequent damage this might have caused after you followed the manufacturers recommendation?

Is it reasonable to believe most consumers feel their Dexcool is good for 150,000 miles / 5 years according to the manufacturers recommendation? Would you recommend following this recommendation?

Originally posted by HercMan:
Put a little logic into this. If Dex was such a bad product then why does GM still continue to use it to this day? You think that if they had a quality issue that could be solved by simply changing coolant they would've done that already? And just how many vehicles have been produced that came from the factory with dex and just what is the percentage of those that actually have problems? Besides if anything GM would switch to the green since that stuff is cheaper to start with. So I'm not one of those anti dex people.

Why does GM continue to use Dexcool? They can claim it lasts longer than regular coolant for marketing purposes and make profits from costly repairs caused by Dexcool (at a minimum water pumps are known to fail on these cars way too soon and I believe that's Dexcool related). Also, GM would need a valid reason to switch to green coolant.. wouldn't it look suspicious if they suddenly changed to a lower-life coolant.. it's like admitting guilt/liability and large corporations don't like to do that.

Btw, after I had the coolant properly flushed.. the car runs so much cooler and even has better acceleration. Nobody has answered my initial question though.. do you think this sludge build-up already caused damage to the engine and cooling system? I would love to keep my car but I'm nervous as hell that I'll have more problems in the future and costly repairs.

If Dex was such a bad product then why does GM still continue to use it to this day?

now i just found this out today, my buddy that works at a dealer said that gm did switch there coolant it might still be called dexcool but the liquid is different. when i get more info ill let you guys know.

GP as for "damage" done to your car I think your a little on the paranoid side. If you say it's running better then before then I'd think any "damage" is minimal and will never be noticed. Like I said before there is way too many GM products on the road and if the stuff was that bad then GM reviews and sales would be in the basement. And by the way did you know that if you ever over temp your motor you need to change the oil? No matter how many miles are on the oil. Excessive heat breaks down the oil ruining its lubricating properties.

I'll agree that people have experienced problems concerning dex but I wouldn't go recommending changing it out ASAP if your not having problems and if it concerns some one that much then just have it flushed out and replaced with the green stuff at your next "winterizing" service window. Just like you did in the old days.

That issue was actually with a lot of cars in the late 80's early 90's. I believe the government mandated that certain chemicals couldn't be used in automotive paint. The automakers had to find a quick solution and the results weren't that good. The technology has advanced now where this isn't an issue. You may see a bunch of 1990 cars around with patches of fresh primer.

On my sister-in-law's 88 chevy, the paint peeled freshly off after she just got it. They did repaint it for free due to the lemon law.