I found this article about Dex Cool anti-freeze and it's potentially causing premature failure on the 3800's LIM gaskets. Has anyone else been aware of this claim or believe there is any merit to it? Have you known any failures to 3800 engines in which Dex Cool was used? Just wondering since we see so many failures with our LIMs at some point.

Link to full article below: Here is a snippet from it. Lots of good pictures and technical experiments he has done.

The potential role of DEX-COOLŽ



The potential role of DEX-COOLŽ in GM 3800 lower intake manifold gasket failures

visit Portal for more information from our very experienced team of gearheads

Introduction

Before you read further, let me introduce myself. I'm not an automotive specialist or professional. I'm an enthusiast, or hobbyist. My interests are primarily focused on the Buick 3800 V6's commonly found in Pontiac Bonnevilles, various Buicks, Chevrolets, and Oldsmobiles. I'm also an Administrator on Portal, an internet Forum for Pontiac Bonneville owners. Over the 6+ years I've been there and the forum it replaced, we have endured countless topics, gasket failures, and blown engines. Our Gearheads on the forum have diligently fought the battles and we've learned a lot about how to help prevent the problems, but never really FULLY understood the root cause. I, among others, have spent countless hours reading on the internet about all the lawsuits, reports, claims, and rumors. I decided to take it a step further using some good analytical approaches, and some nice tools available to me at work. I design and build custom research and development laser systems for Hewlett Packard.


This page is primarily focused on the failure of lower intake manifold gaskets in GM 3800 motors. These are pushrod V6 engines with cast iron blocks and cylinder heads. The motors are renowned for being 'bullet-proof'. Some are supercharged from the factory, and many are pushed to the limits of performance by other enthusiasts. While other GM engines have had the same problems, I'm only going to briefly touch on them in this report. I've long suspected DEX as being the primary culprit in early lower intake manifold (LIM) gasket failures, but to this date, nobody has proven it. I won't prove it in this report either, but the grim reaper may be pointing a little more emphatically in that direction by the time he finishes reading this.

Goals

The goals of this report are simple:

1. To attempt to dispel the rumors about some of the possible causes of early gasket failure in these engines.

2. To attempt to reveal all the possible variables that may play a role in these failures.

3. To invite yet more controversy and discussion on the topic, and perhaps encourage someone to investigate further.

The investigation starts

I have 2 sets of gaskets to compare that are good candidates for this report. The first set was removed from one of my own cars, a 1995 Pontiac Bonneville SE, with the supercharged engine as a factory option. The gaskets are OEM as installed from the factory and were removed at 125,000 miles as routine maintenance, the car was not originally 'equipped' with DEX (had the old-school green glycol stuff), and to the best of my knowledge never slurped the DEX at any time in it's life (the original owner's son-in-law is a Service Manager at a GM dealer, and knows better.....I bought the car from them). The second set is from a 1998 Pontiac Bonneville SE, and these gaskets were installed sometime after 2002 when the upper intake manifold was replaced due to a presumed failure. The UIM has a manufacturer's date of 2002, and the Gaskets were manufactured in 2001. 30k to 40k are the estimated number of miles that these gaskets were in the car. It's unknown if the car had a coolant flush at the time of gasket and UIM install, but it is presumed (the work happened at a dealer, and GM dealers know about DEX's ability to turn acidic over time).

 

IMO:

I think the DexCool eventually deteriorates the Plastic UIM/ LIM...thus, Causeing them to leak!

Not to mention the EGR tube heats up and also causes further failures...

That was certainly the case on Mine!
IMO

 

Really? Thanks Dave for your input. Well that's one vote to validate this article.

 

I'm not sure if its the dexcool, or them using nylon intake manifold gaskets. After my car had them replaced I was talking with my mechanic he's a tech at merollis chevorlet, senior tech I would imagine. I asked him about the 3.8 motors being destroyed because of dexcool, and he said your car has the good motor, there was a monte with a 3.4 across the shop and he showed me that one and said this is the one that blows. I did a lot of researching about dexcool before I even got the car, and it seems like most problems arise when the coolant gets contaminated, even air getting to it contaminates it. They also messed up with the 5yr/or 150,000 mile coolant maintenance. People who own saturns never had an issue with dexcool, since its never exposed to the air, at least that was there logic.

 

I use to work at Merollis Chevrolet.
Back in the 70's (Man am I old)
Thats when Cars were Cars...
The Vettes,Chevelles, Nova's, Camaro's

 

Interesting to note. Guess a good mechanic would try to understand why he's seeing issues and work to resolve them to eliminate call backs. And 1 vote for Dex Cool

 

I changed mine at 120k and the gaskets looked fine, only reason I changed em is I had the motor most of the way tore down for paint I'm no longer running Dex in mine though

 

This topic gets brought up a lot. Here's what I can tell you:
#1 - Nylon is a HORRIBLE gasket material PERIOD!

I have seen cars from the factory, never had a drop of DEX and the nylon LIM gasket fail about the same time/milage as DEX filled cars.
The nylon cannot take the hot temp of heated fluid on it. This is the source of the problem.
A good example are the mid 90's 3100 Grand Ams. I've worked on a fair amount of them. They never had a drop of DEX. I change the LIMs TWICE on my old one (90K miles on both sets that had to be removed).

#2 - Original DEX was found to be somewhat corrosive (hence why, yes, GM lost a class action lawsuit). The formula in modern DEX (I believe late 90's, definately 2000 and newer) is revised and safe. It does have a tendancy to get "sludgy" if not maintained and exposed to air.

Everyone is entitled to believe what they want, but from my experience DEX is no more harmful then water to the LIM gaskets.

Food for thought:
- GM lost a HUGE class action law suit, which results in a lot of bad press (and these stories resurfacing). After loosing a lawsuit like that and how public this information was on DEX, I would hope if DEXreally was still a problem GM would discontinuing use of DEX (but they still put it in new cars).
- If DEX is this corrosive to the LIMs, why does it not break down radiator hoses or over flow bottles? I suppose the answer is they are not Nylon based. Again, Nylon=bad gasket material.

 

Actually, DEX is less harmful then water. It has anti-corrosive properties, lubricant for the water pump and raises the boiling point when pressurized. Water provides none of those benefits.

I suspect that article was written prior to the revised formula of DEX that is on the market now. It is safe to use.

 

BTW - I read that article ZIPPY posted years ago. I admit, I admire the effort, information and perspective leading to the drawn conclusion.
Unfortunately, this independant study revolves around two different vehicles (which is a nice test case).

Not sure how much of a different is makes, but I believe they compared a Series I 3800 vs a Series II 3800 (not sure if that played a factory). Also, it's clear the gaskets and UIM in the '98 Bonnie were changed once before (not sure if they were as good or better then factory or the manufacturer of them).

It could also be dumb luck.

Again, based on my experiences, I feel DEX is not a factor in LIM failure. Average life is 80K-120K for LIM gaskets on 3100/3400/3800.