GM Dex-Cool Dilemma

I’m not sure if this issue was ever settled, but some say the issues with GM intake manifold breakdowns (on the 3.1, 3.4, and 3.8) is due to the use of dex-cool; others say it’s just a flawed plastic gasket design.

As such, some say when it’s time to replace the gasket, just use one of the upgraded aftermarket gaskets and continue to use dex-cool, but flush it regularly. Other say get that dex-cool crap out of there and go with X (I’ve heard use the old green, use Mercedes coolant, or the Japanese pink).

What say you?

I flush it all out and use the good old green stuff. The gasket design is fine. Dex-Cool is the problem because at some point it’s going to get exposed to air by way of a bad radiator hose, leaking water pump or any other of a hundred reasons. When that happens…rust forms inside the cooling system. The green stuff leaves a protective film that prevents rust. Dex-Cool doesn’t so that’s why it’s not suitable for use in any vehicle radiator or engine block.

The intake manifold gasket design was flawed on these engines. The silicone bead that was laminated to the plastic frame would delaminate from the frame from heating/cooling cycles and start leaking.

I know people who got rid of the Dexcool and switched to a universal coolant and still had an intake gasket failure due to the poor design.

Flush the Dexcool out and replace it with a universal coolant and you’ll be good to go.


The gasket design was the problem

If you’ve ever replaced these gaskets, you’ll see that the new design is much better

The gasket design was also the problem on the 4.3 and 5.7, among others, by the way

I think I just bought a 2004 Grand AM.

I’m sure I’ll be seeing them soon enough. :stuck_out_tongue:

Others will disagree but I haven’t had a bad Dexcool experience. When I bought my G6 I was concerned about it. Two dealers and and independent all told me its not a problem as long as there are no leaks and air does not get in and it is changed out on schedule. After four years I haven’t had a problem. It was drained and replaced a year or so ago when I hit a raccoon and wrecked the radiator. I’m ready to do it again as soon as it warms up again.

The gasket material was the problem. I had a 1988 caprice which started leaking and the specialty guy at the rad shop said “intake manifold gasket” without even looking under the hood. He did not do the replacements himself, but referred me to another shop that did many of these repairs. They changed it out with a better gasket for $140 and I had no problems after that. The car did not have DexCool in it.

I’ve used Dexcool and never had a problem with it. I have had intake manifold gasket issues with GM cars that the coolant didn’t even go through and the area that failed. The fabric gasket with the silicone bead failed on me twice in my Saturn, and after market gasket lasted.

While I don’t have any issues with Dexcool, I usually use the universal long life because it is just as good and easier to come by (and sometimes on sale). I do stick with the trusted brands though, but I pick the brand on sale when I need it.

Sheesh, Bing, you must have big raccoons in your neck of the woods.


How the heck did you get a manifold job done for $140?

Prices around here are Dealership:$900, Independent: $350+, Side Job: $200+byop

@Demo_Beta It was just the intake manifold gasket, and this was a super low overhead shop; one guy did everything. However, I misquoted. The actual cost by a guy named Larry was $255.52 including sales tax. This guy had done so many that he could do V8s and V6s virtually with his eyes closed.

@insightful Probably normal size raccoon but humped a little crossing the road. He was high enough to take the air dam out and right behind that was one of the radiator supports soldered to the radiator. Broke that off and that’s all she wrote for that one. Insurance agent wanted to know if it was a live one or dead one. I said he was live but died shortly after, and in that case it was an act of God and they paid. At any rate I got my Dex replaced.

Dex-cool is not the problem. Poor gasket design is/was the problem. As long as the cooling system is sealed and full there is no reason to believe you can’t get 50,000 miles from Dex-cool.

I’ve Used Dex-Cool In Many GM Cars, For Many Years And Hundreds Of Thousands Of Miles And Never Once Had A Problem. Follow GM’s Coolant Change Recommendations.

I’ve got three very happy GM cars (2 Chevrolet Impalas, 1 Pontiac Bonneville) in the driveway, all run exclusively on Dex-Cool since new, and if they could talk, they’d back me up on that.


I feel that Dex-cool is just fine, as long as it’s changed every 5 years, and you don’t let the coolant level stay too low

But if you don’t service it on time . . . and realistically, most people don’t . . . it may very well partially solidify and plug up your radiator and/or heater core

But then, on the other hand, any coolant that is neglected is bound to cause problems

I’ve flushed out plenty of heater cores, on neglected non-gm cars that didn’t use dexcool

I’ve even “fixed” a few complaints of engines operating too hot, which were caused by old, degraded coolant. I used parentheses because replacing the coolant is actually maintenance. But if changing the old coolant takes care of the high coolant temperature, then I guess you might consider it a fix

So I talked to a friend of mine in the performance industry and he said that he’s pretty sure GM starting putting in the “new” or “upgraded” manifold gaskets at the factory during the second half of the 2003 production line and onwards; at least on the 3.4.

Anyone know if there is truth to this?

Well, I’ll say this . . .

I came across a GM bulletin the other day. It said that starting the 2004 model year, the 4.3 got the upgraded gaskets

So, I’d say your friend is probably right

Went with peak global at 85k, no dexron no problem imhop.