Dex-Cool

[Ranger]

Those of you who have not seen this might find it interesting. It gets very interesting at post #26. Draw your own conclusions.

http://www.cadillacforums.com/forums/north...2-dex-cool.html

[Bruce Nunnally]

Previously I had access to one of the GM forum sites where GM dealer mechanics were able to post and share hints and tips on repairs. It was very interesting to read what issues they were running in to with different Cadillacs, although mostly they would post really odd symptoms of course, since anything "regular" they knew the answer to.

One thing that came through clearly though was that the mechanics were not that impressed as a group with the cars. As I have mentioned, one mechanic referred to the Catera's as "caterables". They also had strong opinions about GMs estimated (allowed?) hours for various warranty repairs, although it was interesting to see healthy debate on how once you got a few of the [whatever] repair jobs under your belt it was not that hard to beat the time and make money on them. I suppose though that there is a natural tendency for mechanics to be critical of engineering design.

I personnally am NOT a master mechanic; I envy people that are, and I wish I had more skills that way.

Certainly dealer mechanics do see the repairs that are required in their shops. However, they frequently don't see the rest of the engineering trade space that was involved in the design. Sometimes it is easy to second-guess the factory design, especially if you don't have the restrictions the factory engineers had in terms of cost and weight and time.

Another complaint I have heard from Dealers is that GM does not listen to their input. I was proudly telling one Dealer an anecdote about how the factory techs had read inputs here and discovered there was a problem and fixed it. The Dealer's response was thank goodness they listen to SOMEONE. I have come to believe that it is very difficult for GM to segregate the noise from the signal in dealer inputs on product. Sure, you can analyze warranty repair data, but we also hear that a ton of the warranty repairs show up as "can not duplicate" when the Powertrain or Cadillac engineers do get to dig into the engine or tranny or whatever the dealer pulled and replaced.

[Ranger]

I hear ya Bruce and I agree. He makes some convincing point though. Fact or not I do not know. Seems to have the credentials, time and knowledge. I only wish Guru was here to debate him. It would be very interesting. Sure does make one wonder though.

[MAC]

I hear ya Bruce and I agree. He makes some convincing point though. Fact or not I do not know. Seems to have the credentials, time and knowledge. I only wish Guru was here to debate him. It would be very interesting. Sure does make one wonder though.

I remember many a post where someone would badmouth GM and challenge the Guru. The challenger would write a big long post, which to the average person could very well sound like he knew what he was talking about. Then the Guru would respond and blow the challenger out of the water and send him home with his tail between his legs.

I remember the Guru saying that Dexcool is fine as long as the cooling system is kept full and is serviced at least as recommended. However, let's bare in mind that it's possible that Dexcool has it's downfalls. Unfortunately, the Guru isn't here to address allegations that Dexcool causes plastic to deteriorate.

[KHE]

One thing to remember with DexCool is to always mix it 50/50 with water (distilled is preferred) before adding it to the system. It is important to keep the concentration at 50/50 - more is not better. The absolute maximum concentration is 60/40.

My '96 SLS has DexCool from the factory and I've owned it since t was 3-1/2 years old - so far, the cooling system has held up. When I repaired the head gaskets on the '97 STS I bought last March, I installed DexCool coolant.

[Regis]

Definitely interesting reading. At the very least it should keep everyone on their toes about "absolutes". It would appear that the solution to preventing coolant related issues is regular maintenance. I believe we have some members that can attest to that from personal experience(s).... and not the good kind. If you're one of those lazy car owners then you reap what you sow. And that would be a lot of head aches. Regular maintenance is king. I think we can all agree on that.

[OynxSTS]

I hear ya Bruce and I agree. He makes some convincing point though. Fact or not I do not know. Seems to have the credentials, time and knowledge. I only wish Guru was here to debate him. It would be very interesting. Sure does make one wonder though.

Ya to that... The observation on one post about Dex-Cool usage starting in 1996/97 correlates nicely with the statistical blip of NorthStar head-gasket issues... Gave me a bit of a sinking feeling when I read that....

Is it true that ONLY GM uses this stuff?

[KHE]

I hear ya Bruce and I agree. He makes some convincing point though. Fact or not I do not know. Seems to have the credentials, time and knowledge. I only wish Guru was here to debate him. It would be very interesting. Sure does make one wonder though.

Ya to that... The observation on one post about Dex-Cool usage starting in 1996/97 correlates nicely with the statistical blip of NorthStar head-gasket issues... Gave me a bit of a sinking feeling when I read that....

Is it true that ONLY GM uses this stuff?

I think the blip in head gasket issues was due to many neglected 1993 engines with the old green coolant. Owners would neglect the cooling system and the head gaskets would fail around the 1996/1997 timeframe.

[Cadillac Jim]

I had dealer warranty repairs that may not have been necessary. The ones that I can remember offhand include:

• Catalytic converter (tyring to fix exhaust heat shield rattle; it still has it).
• Serpentine belt at 9,000 miles. I didn't change it again until 100,000 miles.

I would like to comment on DexCool compatibility with plastic. I ran DexCool in my car from the day I got it, including the 7 years without a change that brought down my head gasket, and there was never any sign of difficulty with plastic parts.

Trained techs are worth their weight in gold. I would have a tech-rebuilt item of any kind that has a warranty, because nothing gets better knowledgeable care than an item being rebuilt by a tech that knows he must fix it free if it comes back. I would rather have a remanufactured Palm Pilot, stereo set, or Nothstar engine than a new one because I have more confidence in it. This is a big part of why I bought a Jasper instead of a new engine last July.

Design, development, and manufacture are a different thing that repair and overhaul. This is a whole different world. Those in the product development world benefit from the knowledge and experience base of repair technicians when they have access to it. Dissecting returned parts is good too and supplements what repair techs can tell you, but the whole is greater than the sum of its parts. I would hope that GM does what they can here.

[GreenMachine]

Someone was telling that the old green was good for cars when changed on time but the main thing behind dex-cool is that its safer to the environment not necessarily to the car.

From the "second hand" wisdom I've goten from this forum that is based on what the guru has said I did a coolant change on my 98 this year and filled it with Dexcool. Did it back in June.

Now when you count those years its 8 years since it was changed, I have no service records for the vehicle, it was just under 60 thousand when we got it.

Headgaskets are always in the back of my head but I can hope the dealer changed it while it was sitting on the lot waiting for its new owner.

The one argument I haven't really heard about dex-cool is this plastic one. Very confusing and intresting.

The question is do Techs just assume its the coolant doing this when its actually something else? Since Dex already has a bad rep it would be easy to throw blame at it for anything and everything.

You may also recall the redesigned waterpump housing which was plastic at one point changed to aluminum...hmmm.

[KHE]

Someone was telling that the old green was good for cars when changed on time but the main thing behind dex-cool is that its safer to the environment not necessarily to the car.

Whoever told you DexCool is safer for the enviornment is misinformed. Green coolant and DexCool are both ethylene glycol. The only difference (besides the color), is the corrosion inhibitor package. Green uses a silicated based corrosion inhibitor and DexCool uses an organic acid based corrosion inhibitor package. The only way DexCool would be safer for the enviornment would be due to the extended drain intervals.

Propylene gylcol is marketed as an environmentally friendly coolant but it does not have the heat transfer properties of ethylene glycol and is not recommended for a Northstar engine.

[GreenMachine]

That article the guy referanced is intresting:

http://www.subscriptsforum.com/boards/subu...ssages/600.html

basically says what we've learned when he concludes what coolant to use, use what the factory filled it with.

[BodybyFisher]

Headgaskets are always in the back of my head but I can hope the dealer changed it while it was sitting on the lot waiting for its new owner.

Yea and I am hoping that Santa will bring me a Snap-On tool set! You don't really think that a dealer would do a head gasket unless they had to do you?, and on their dime?

[Cadillac Jim]

I think he means that he hopes that the dealer changed the coolant, not the head gasket. Actually, I think the chances are slim to none that the dealer did anything except wash the car.

However, I don't think that very new coolant would go bad over time the way that it would in a car that is driven occasionally. I would have the coolant tested for anticorrosion capability and for combustion products, and if it tests OK on both counts I would just change it and quit worrying.

[BodybyFisher]

OH good, I read that WRONG!!! Thanks JIM, sorry EGREEN.., I read that as CHANGED the HG's...

Im still hoping SANTA is good to me however..

[OynxSTS]

Ya to that... The observation on one post about Dex-Cool usage starting in 1996/97 correlates nicely with the statistical blip of NorthStar head-gasket issues... Gave me a bit of a sinking feeling when I read that....

Is it true that ONLY GM uses this stuff?

I think the blip in head gasket issues was due to many neglected 1993 engines with the old green coolant. Owners would neglect the cooling system and the head gaskets would fail around the 1996/1997 timeframe.

That's not what I was saying... lots of us have noticed that the vast majority of North*s with head gasket problems were model year 97... with the next largest batch being model year 1998... They didn't fail in 97/98 they were built in 97/98.

If you do a search of the historic posts on this and other forums, you will find that at least 8 times out of 10... Threads that start with something like "My Northstar needs to be timeserted" will be discussing a 1997 or 1998 model year car.

The statistical correlation with the introduction of DEXCOOL in 96/97 is troubling.

On the other hand "stats" was my worse course in University... (C-... barely )

[clarkz71]

That's the point I was trying to make on the other forum. I've seen alot of weird cooling system problems with dex-cool in my vehicles and those I've worked on as a technician.

[KHE]

Ya to that... The observation on one post about Dex-Cool usage starting in 1996/97 correlates nicely with the statistical blip of NorthStar head-gasket issues... Gave me a bit of a sinking feeling when I read that....

Is it true that ONLY GM uses this stuff?

I think the blip in head gasket issues was due to many neglected 1993 engines with the old green coolant. Owners would neglect the cooling system and the head gaskets would fail around the 1996/1997 timeframe.

That's not what I was saying... lots of us have noticed that the vast majority of North*s with head gasket problems were model year 97... with the next largest batch being model year 1998... They didn't fail in 97/98 they were built in 97/98.

If you do a search of the historic posts on this and other forums, you will find that at least 8 times out of 10... Threads that start with something like "My Northstar needs to be timeserted" will be discussing a 1997 or 1998 model year car.

The statistical correlation with the introduction of DEXCOOL in 96/97 is troubling.

On the other hand "stats" was my worse course in University... (C-... barely )

I see what you mean - I think the popularity of these forums (and the internet in general) was not as great 10 years ago when the '93 - '95s would have failed due to poor cooling system maintenance.

[adallak]

Ya to that... The observation on one post about Dex-Cool usage starting in 1996/97 correlates nicely with the statistical blip of NorthStar head-gasket issues... Gave me a bit of a sinking feeling when I read that....

Is it true that ONLY GM uses this stuff?

I think the blip in head gasket issues was due to many neglected 1993 engines with the old green coolant. Owners would neglect the cooling system and the head gaskets would fail around the 1996/1997 timeframe.

That's not what I was saying... lots of us have noticed that the vast majority of North*s with head gasket problems were model year 97... with the next largest batch being model year 1998... They didn't fail in 97/98 they were built in 97/98.

If you do a search of the historic posts on this and other forums, you will find that at least 8 times out of 10... Threads that start with something like "My Northstar needs to be timeserted" will be discussing a 1997 or 1998 model year car.

The statistical correlation with the introduction of DEXCOOL in 96/97 is troubling.

On the other hand "stats" was my worse course in University... (C-... barely )

My neighbor just bought a GM van with blown headgasket. I asked what year. 1997...

[Cadillac Jim]

My coolant was changed in 1999 at 30,000 miles because a tech twisted off the surge tank hose fitting and clamped it back on the nub, and when I brought it in with vast coolant leaks I insisted that the coolant be changed, and paid the $125. Five years later in another state, when the coolant hit 5 years, the tech told the service manager that he wanted to talk to me. He said that the head bolts would pull out because of a fundamental engine design weakness, it burnt a lot of oil (which it started to do when this tech started servicing it but never did before -- and I cured most of it when I went to others), and that Cadillac had re-designed the Northstar V8 "because they had to" and that I should trade my car in. When I said that the new Northstar design wouldn't go in my car, he hung up on me.

Not a word about a coolant change. Two years later, I was looking at a head gasket issue.

I'm convinced that the Service Manager had no clue about the coolant change issue. The tech might have; I'm convinced that he was skipping oil changes or using cheap oil because the car had never burnt a drop of oil until this tech started doing the oil changes. It went from no oil burned (perhaps a half quart burnt in a 3,000 mile oil change interval) to a quart every 800 miles or so in two oil changes – about three months. Then, it would burn two quarts in about 1,000 miles after a change, and I would put in one quart of Mobil 1 10W-30 and the oil consumption would decrease and the engine would smooth out. Later I took to using two pints of CD-2 oil detergent additive (not the CD-2 blend that "adds viscosity") and add Mobil 1 after that, because I was convinced by that time that the tech was skipping oil changes. I flat caught him doing that later and dropped the dealer for regular service after that. A few months later the overheating started and after research here and elsewhere I got a Jasper remanufactured engine. Now, with service that I can trust, I've brought my car back to like-new condition overall and am more satisfied with it than I have been in years.

[OynxSTS]

If you do a search of the historic posts on this and other forums, you will find that at least 8 times out of 10... Threads that start with something like "My Northstar needs to be timeserted" will be discussing a 1997 or 1998 model year car.

The statistical correlation with the introduction of DEXCOOL in 96/97 is troubling.

On the other hand "stats" was my worse course in University... (C-... barely )

I see what you mean - I think the popularity of these forums (and the internet in general) was not as great 10 years ago when the '93 - '95s would have failed due to poor cooling system maintenance.

I hope you are right... What is interesting is that for the 2+ years I've been on this an other Caddy forums the year range of Headgasket cars hasn't changed... when I first joined they were mostly 97s... 26 months later they are still mostly 97s...

It could be:

1) A fluke/coincidence

2) Something else is causing the statistical blip (like 97 was a big year for these cars... was it?)

3) Some economic factors at play here... maybe 97s are holding there value enough to justify timeserting (are they?)

3) A bad batch of gaskets

4) A good batch of gaskets that was designed for green coolant but they melt in orange

5) None of the above.

I don't know...its a mystery and probably always will be... Just like the 3.0L Toyota engines sludge up; they claim they changed nothing but the bore (ya right) and the sludge problem goes away...

DEXCOOL has been proven in lots (hundreds of thousands) of aluminum block LSx engines with no issues...

GM has admitted to gasket issues in the past... (not on North*s though) that would be my bet...

[clarkz71]

Wasn't Kevins car he bought with the bad headgaskets a 97 ??

[KHE]

Wasn't Kevins car he bought with the bad headgaskets a 97 ??

Yep. I bought it knowing it had bad gaskets - the dealer screwed up the first repair by instelling the Timeserts too deep in the block.

[clarkz71]

Yes, I remember your post about buying the car, I just didn't remember if it was the 96 or 97.

[Cadillac Jim]

I think that the fact that most recent head gasket posts are about 1997 model year Northstars is due to the obvious:

1997 START

2001 Four year lease ends, or trade-in at four years. Dealer recondition includes coolant change.

2006 Coolant changed at dealer times out at five years.

2007 A year of old coolant == head bolt pulls out.

It's the ten-year-head-gasket-itch.