I need info on Dexicool

My girlfriend has a 2000 Pontiac Grand Am 3.4 v6, 76,000 miles. Over the last couple of weeks we were losing a bunch of coolant. The coolant is a nasty jelly filled with a nasty precipitate. When I couldn't find the leak, I took it into a shop, where they said the Intake manifold was corroded from the Dexicool that is required by the owners manual. When I called Pontiac on it, they told me to take it to "their authorized dealership". When we took it there, they claimed that there is nothing that shows that the intake manifold is corroding. Course, they didn't say anything about the leak, instead trying to stonewall me with the idea that there are some belts that need replacing. What the hell does that have to do with my coolant leak?!?!?!?! So what i would like to know is what have y'all noticed about Dexicool being corrosive? What about intake manifold? Aren't they supposed to last beyond 76K miles? This is crap and I would like your expertise on the matter, as I may sue Pontiac in small claims court on the subject.
Thanks :smokin:

There is a very well known problem with intake-manifold gaskets on 97-02 (or so) 3.x engines, The gaskets are bad, not the coolant, and there is a newer gasket available. If she got 76k before leaking, shes lucky. If it is the gasket, you may very well be able to see it by looking at it. Could be either coolant or oil

I had the 3.4L in my Pontiac Montana, And yes I had a bad intake gasket. I asked about the gasket on the Montana Forum and quite a few of the respondants said they too had bad gaskets. The 3.4 is known for the bad factory intake gaskets because they are made of plastic. The new ones are not plastic...but if you have a small shop do the work make sure they also put in new bolts to ancor the manifold, or make sure at the very least they use lock tite on the bolts. Not too long after the intake gasket was changed I replaced the can position sensor and found the intake bolts had loosened to the point that I could remove them with my fingers.

As for the Dexcool there seems to be a great debate going on about its effects and side effects. I am indifferent because I change my coolant often enough with a flush each time and have not had any major issues. Although, I did begin to see the gel that you mention in my oil cap prior to my trading in the Montana, some people told me it was from the "High Milage" oil that I was using others said it was from a bad head gasket and the dexcool was getting in to the oil. Unfortunately I never found out the actual cause, I got rid of the van before getting into the cause.
As for the Dealer telling you that you need to replace the belts, that is typical, they are going to try to get you for a belt change then when you continue to have the original problem and take it back to them they can then hit you for the gasket change. I have seen things like that go on, it is too bad that that stuff goes on in the industry.

Good luck,

Something else to be aware of as well, if anyone has mixed green and pink coolant and run the mixture for a while, it turns into a tar-like substance. When I bought my GAGT with 93k miles on it, the radiator was plugged almost solid from a body shop having mixed the two coolants together about 8 months before.

Get a good radiator flush chemical, and a backflush kit. Like Hoags states, regular flushing!!!

Drain the radiator enough to introduce the rad. flush chemical, run it per directions. U may have to run it twice [meaning run it, backflush it, run it again and backflush it]. Do it in one day when ya can get the ride to good operating temp.

Run the chemical, backflush, refill with water only, run the ride, do it all again, and refill with proper coolant. Prestone has a new coolant that is interchangeable between the "green" and the "red", use that.

Dexcool sucks. Get it out of the engine as soon as possible. And thats incorrect if you mix green with dexcool it make it even more corrosive. Dexcool by itself it garbage. A 100000 mile antifreeze that most mechanics recommend changing every 36000.

who said anything about mixing the 2 coolants making it more corrosive?

skibum1111 You said the dexcool with the green make it look like tar. It will after it leaks out since when you mix dexcool with regular antifreeze it becomes super corrosive and will eat all your gaskets. THe tar look is the dexcool burning off.

Get a good radiator flush chemical, and a backflush kit. Like Hoags states, regular flushing!!!

Drain the radiator enough to introduce the rad. flush chemical, run it per directions. U may have to run it twice [meaning run it, backflush it, run it again and backflush it]. Do it in one day when ya can get the ride to good operating temp.

Run the chemical, backflush, refill with water only, run the ride, do it all again, and refill with proper coolant. Prestone has a new coolant that is interchangeable between the "green" and the "red", use that.


Good suggestion. The Prestone Extended Life 50/50 is great stuff. Its green and safely mixes with Dexcool and does not cause any corrosion in any domestic or foreign car. Just in case the flush doesn't get all the old Dexcool out. At least you can sleep peacefully.

I run the stuff in my GTP and the best part is you don't have to worry about the Dexcool sludge in the coolant reservoir tank anymore.

Just my 2 cents. :2cents:


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Thrasher CAI, DHP v1.0 ECU, Granatelli CAI Tuneable MAF,
3.4 SC pulley, Hi-Flow CAT, u-bend delete, 180 TS,
TB spacer, MSD 8.5mm wires, AC Delco 41-932 spark plugs,
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ET: 14.3 @ 96 mph

Awesome, thanks yall

It's all fine to want to dump Dexcool, but one reason dexcool is used is because it is safe for aluminum parts (like the heads). Keep that in mind when hunting down a new coolant.