GM Owners

[g1g]

I also have a 1999 Chevy van with a 350. This past year I noticed the lifters making noise. I found out if I changed the oil and filter it was fine. It wasn't long before the lifters were making noise again. My thoughts were the filter was letting the engine drain and when I changed the oil and filter again it stopped only to start back up in a few weeks. After questioning a mechanic on allexperts.com He said the intake manifold may be leaking antifreeze in the oil. I had my doubts but noticed I did need to add water in the radiator. I decided to try block seal and at the same time spoke to another mechanic. I really couldn't believe it. He said that the GM DexCool antifreeze was eating the gaskets in many of the engines and to Google DexCool and I would see many lawsuits involving this. After doing this I found many engines ruined because of this. I think I caught mine in time as it has been almost 2 months since the block seal and all seems fine. I was also told that DexCool will not show the white color when mixed with oil. I run Mobil 1 and it didn't show anything.
So anyone that has this, you might consider flushing it out and replacing with the old fashion stuff.

[markopolo]

Very interesting. Wow, a Google search turns up a lot of complaints.

Here's a link with some good info:

http://www.getahelmet.com/jeeps/maint/dexcool/

It might help people avoid problems.

As for deciding when to change your antifreeze, don't go by miles or you WILL certainly have seal and mechanical failures. One interesting spec I found is to use a multimeter. You put your negative probe to the negative post on your battery. You then place the positive probe in the neck of your radiator, making sure that the positive probe touches nothing but the antifreeze. Make sure the coolant is warm but not HOT (this is for SAFETY reasons as well as accuracy of your readings. Always be careful when opening the radiator cap on a warm engine). Your readings (regardless of negative symbol on readout) should be:

* 0.2 V to 0.5 V - antifreeze is still good
* 0.5 V to 0.7 V - antifreeze is borderline
* 0.7 V or greater - antifreeze is unacceptable.

You can also use test strips (available at a quality auto parts store for $5 or less), they work on both green and red types too. But if you already have a multimeter, why go buy test strips? The multimeter is the more technically accurate method anyway.

I'd never heard of using a multimeter.

Another way to ensure longer life of parts and get better corrosion protection is to make sure you USE DISTILLED WATER when mixing with antifreeze. By just using regular tap water you contaminate the new Dex-Cool and drastically lower the corrosion protection. Distilled water barely costs 59¢ a gallon in my area. So there's no excuse for spending $7.99/gallon on Dex-Cool and then ruining it because you're too lazy to add 59¢ a gallon distilled water to it.

Using distilled water makes sense. Also, use distilled water when topping up your batteries.

[Mike]

I wonder if I should be worried?
What would be the most likely symptom of a problem with the Dexcool
or the gaskets?

[Mike]

I noticed I was using a little more coolant than normal over the past month or
so, and also noted a small stain on the driveway last week after a local road trip.
Took it in to local GM dealer today, and they say it's the intake manifold gasket.
The repair estimate is around $1000. Includes a new serpentine belt (woohoo!!!! ).
Of course I asked about the relationship between Dexcool and these problems.
Apparently there hasn't been a proven correlation between Dexcool and the intake
gasket deterioration, according to the shop guy. He also said that if you flush your
system at least every 3-4 years, you shouldn't have any problems. I see where
using the green coolant instead, and not flushing it every few years, is just as bad
for your gaskets, etc.. Maybe it's not just Dexcool?
My van has 180,000 kms on it. The coolant was flushed in Fall 2009 by me.
It might have been the only flush since new, as I'm the 3rd owner.

Comments? Am I correct in assuming this is more widespread than just my vehicle?
Is there any point in switching to the general purpose "green stuff" I see mentioned
on various blogs and websites regarding this issue? Getting away from DexCool?
I just called the dealer ship back and asked them to flush me, and replace the Dexcool
with the "green stuff". They said "no problem", almost as if they were relieved that
I called back with my request. Peculiar?

[booster]

I don't remember all the correct chemical basis for the types of anti-freeze, but I did a bit of reading on the subject a couple of years ago, when deciding whether or not to switch our 07 away from Dex-cool. Don't believe the dealer, they have had lots of problems. Sludged up 4.3 engines, failed gaskets on lots of others.

The Readers Digest version would be:

Dex-cool is not the best choice, but if changed more often than recommended it will not eat gaskets, plus the newer engines have improved gaskets. The most important thing is too make sure there is never any air in the radiator. Make sure the coolant tank is at the right level and the hose clamp not sucking air. Air and Dex-cool seem to be the fatal combination.

Using plain old green antifreeze has been done by lots of folks, mostly with good success, but it does not have the best corrosion package for modern, lots of aluminum and alloys, engines.

Best choice to go for when getting rid of Dex-cool would be a Honda style anti-freeze. As I said, I don't remember the actual types, but the Honda style has the corrosion inhibitors for the newer engines, but a different chemistry that gets rid of the Dex-cool type problems.

That said, I decided to wait until the 5/100K warranty is off our 07 (Oct of 2013) to switch from Dex0cool, as the change would void the warranty, but will be changing it this year at 10K miles. After that it will be on Honda spec anti-freeze.

[Mike]

Originally Posted by booster

I don't remember all the correct chemical basis for the types of anti-freeze, but I did a bit of reading on the subject a couple of years ago, when deciding whether or not to switch our 07 away from Dex-cool. Don't believe the dealer, they have had lots of problems. Sludged up 4.3 engines, failed gaskets on lots of others.

I was a bit surprised when they said intake manifold gasket, as I thought it mostly affected smaller
displacement GM engines, like those you mention. I was expecting it to be a water pump, based on where the
coolant was found under the van.

Originally Posted by booster

The Readers Digest version would be:

Dex-cool is not the best choice, but if changed more often than recommended it will not eat gaskets, plus the newer engines have improved gaskets. The most important thing is too make sure there is never any air in the radiator. Make sure the coolant tank is at the right level and the hose clamp not sucking air. Air and Dex-cool seem to be the fatal combination.

I did read that about the air issue. It made me wonder about the coolant recovery reservoir, and generally how
you could prevent air being sucked into the system? I have never removed the rad cap, as I have never needed
to, using the reservoir to add coolant if necessary. I also wondered if it might be more than the coolant,
perhaps the gaskets themselves are lousy, or the design of the heads, manifold, block channeling is just
more prone to problems? So changing coolant types might not buy you much in the long term.
When I asked, if I stayed with DexCool as my coolant choice, whether I'd have to do this again in another
180,000 kms? Answer, non-committal. I asked if the gaskets had been improved or were they using a better
grade of gasket (mine is a 2002)? Answer, again, no, it's a factory gasket replacement.
That made up my mind to switch, more or less. DexCool and a factory gasket had failed for me, so why not
try something else?

Originally Posted by booster

Using plain old green antifreeze has been done by lots of folks, mostly with good success, but it does not have the best corrosion package for modern, lots of aluminum and alloys, engines.

Saw a fair number of people mention it as a possibility, and if it's less prone to error (air exposure, less acidic,
less corrosive) it might make more sense for the masses. Some people have no idea about changing fluids
at regular intervals. Throw in DexCool with it's apparent, and undocumented, shorter lifespan and you're bound
to have issues like this. I tend not to add extra water to my coolants up here on the tundra, in my Escape for
example, and have never had any other gasket problems, with any other car, ever. I've owned a dozen or so,
all shapes and sizes.

Originally Posted by booster

Best choice to go for when getting rid of Dex-cool would be a Honda style anti-freeze. As I said, I don't remember the actual types, but the Honda style has the corrosion inhibitors for the newer engines, but a different chemistry that gets rid of the Dex-cool type problems.

Got a brand name, even? I'll be switching to the green stuff as of this week, and if there's a better "green stuff",
I'd love to know more about it. I don't want to have to do this again, not that this engine will likely see a ripe old
age, but they didn't mention any other side effects from this problem. I believe it's been caught in time. I haven't
noticed any performance or other symptoms of fluid cross contamination. Everything will be changed after the gasket
replacement, on spec. And time, of course, will tell. I'll ask at my nearest Honda dealer, or maybe Canadian Tire
about their version of coolant.

Originally Posted by booster

That said, I decided to wait until the 5/100K warranty is off our 07 (Oct of 2013) to switch from Dex0cool, as the change would void the warranty, but will be changing it this year at 10K miles. After that it will be on Honda spec anti-freeze.

I don't have the warranty issue to wait on, so I'm pulling the trigger now, and switching to anything but DexCool.
I wonder if the green stuff comes in GM/Ford/Honda/etc. versions? Or is it "one size fits all"?

[booster]

Here is a link to a class action suit settlement. Yep, no problems--right.

http://www.stuevesiegel.com/CM/Resul...ON-LAWSUIT.asp

A quick look says the Dex is OAT chemistry, Honda is HOAT. Organic acid technology vs Hybrid organic acid technology.

There is lots of info to by digested, and some newer formulations also. If you do a couple searches, you will get more info than you probably want to know, or read.

[Mike]

I noted the engines listed as Group A,B,C were all V6s ranging from 3.1 to 4.6 litres displacement.
No mention of any V8s.
Looks like the bankruptcy proceedings of 2009 also spared them from additional damage from
these class actions.
I'll have a browse on the OAT versus HOAT stuff, sounds interesting.

Thanks.

[Mike]

Done. Replaced gasket and sundry shop supplies including switch to the "green stuff"
which is now the "yellow stuff". I had a quick look under the hood when I picked up
the van, and was surprised to see yellow liquid in the recovery reservoir. I had to ask
and was told it's now yellow. I also asked about the water pump and was told no signs
of problems with it, or any other ancillary fallout.
So parts $200,
labor $700,
tax around $120.
Total just over $1000.
Oh, well........