Dex-cool = Dex KILL?

[pancho400cid]

My beater is a 2001 Saturn SC2.... I know... total *****-dropper right?

Intake manifold is plastic and prone to cracking at the heater hose connection. Long story but mine cracked and there is a kit where you remove the intake, saw off the offending parts and replace with aftermarket metal kit. Done.

I replaced the coolant. I did not actually check the manual but thought I recalled it called for "Dex-cool"... so that's what I bought.

Never heard of it before tonight but 100% by coincidence I see a youtube vid that says Dex-cool forms nasty sludge when contaminated with air due to leaks or whatever. The vid showed a motor that was NASTY in all the coolant passages (intake manifold removed).

My car leaked for a long time BEFORE I fixed it. I did not notice any sludge in the intake when I did the repair.... but should I worry about this... like enough to change out brand new coolant? I think I'm air-tight for now (fingers crossed).

 

[Richard Cranium]

I flushed out the dex-cool and reinstall good old anti freeze.
But don't mix them. Make sure that you flush it out good or it also turns into a glue.

 

[DeltaWye]

You're going to get a lot of varying (and strong opinions on this). I have a 2005 Pontiac and when I had to drain the coolant for some reason a couple of years ago I read up on Dex-Cool and decided to just use the generic Prestone. After flushing what I could with the garden hose, I filled it up with water and some "Radiator Flush" which is some form of detergent and ran it for a day, drained it and did it again with just water (this was during the summer). Then I drained it again and I put in the new coolant.

I think the problem with Dex Cool was that people left it in way too long because GM said they could. I don't remember the details but I believe they shortened the service interval after the fact. If you haven't seen this video, it's a hoot:

 

[pancho400cid]

Holy Cow!

The radiator in that vid (9:45 in) is CRAZY. How was that thing even running?

I did zero homework on the Dex-Cool... I just thought it was about corrosion with modern radiators or something.....

 

[DeltaWye]

Holy Cow!

The radiator in that vid (9:45 in) is CRAZY. How was that thing even running?

I did zero homework on the Dex-Cool... I just thought it was about corrosion with modern radiators or something.....

The 3.8s are great engines! Shame they stopped making them.

My car did have the typical orange/brown film but nothing had solidified. Not sure when the coolant had last been changed. My reasoning was, the Dexcool may be problematic or it may be fine, but I've never had a problem with the green stuff in other cars so what harm will it do to switch over?

 

[cajunfirehawk]

Yeah, long standing issue, the important thing is, you changed it, period.

 

[wasfuzz]

Had a trailblazer that no matter what you did every 8 months if you did not flush it the heater core would plug like you would not believe. Hook it up to the air/water pressure flusher and it would blow molasses out of the core. Switched to reg anti-freeze and never had a problem.

 

[wssix99]

My beater is a 2001 Saturn SC2.... I know... total *****-dropper right?

This is the type of car you want to put Dex-Cool in. It lasts much longer (between changes) than the green stuff and is more forgiving of abuse.

If it starts to oxidize and gel - you either have gone too long with it or you have larger problems going on with the engine and the coolant is just a canary in the coalmine...

 

[Iron-Iceberg]

Also don't mix it with tap water, I think this is what causes a lot of the problems. Use distilled water.

 

[RWorth]

The important thing with antifreeze is to watch it, All the new antifreezes you buy over the counter are made to work with aluminium, so any of them can be used, just check it every year and make sure it's staying clean, if it's not flush and repeat. I owned a radiator shop for 20 years, the only antifreeze issues we ever had was with cheap antifreeze, some of the cheap brands would coagulate in the system and make a mess. Any of the major brands should be good.

 

[Hotsauce]

I think dexcool becomes a sludge problem when mixed with other coolants as well. On a my GP GTP's I flushed out all dexcool after the lower intake manifold job. Most of the GM v6 motors were known for blowing intake gaskets = coolant in oil and vice versa = sludge on bottom side of oil cap. No doubt the dexcool would start developing sludge too.

 

[Hotsauce]

http://www.underhoodservice.com/under-pressure/

 

[slow]

Also don't mix it with tap water, I think this is what causes a lot of the problems. Use distilled water.

This.

I have only used dexcool in my GM vehicles (1998 WS6 and 2006 GT0) The WS6 I drained the radiator and filled every 2-3 years and the GTO replaced the dexcool with more dexcool (mixed with distilled water) after 6 years and 30K miles, came out same color as the new stuff.

 

[gungatim]

I've been getting a lot of plugged heater cores the past couple years from dex-cool filled cars. it seems to be getting more and more common, mostly on cars around the 10 yr. old mark.

IDK if it is improper mixing, water, time, or what, but I now tell everyone I deal with to flush that **** and refill with good old ethylene glycol if the vehicle is older than 5 yrs...I've taken to using a 5 gallon bucket and small pump to backflush cleaner through the system for a few hours...nasty snot and black junk usually comes out after a while...

 

[pancho400cid]

http://www.underhoodservice.com/under-pressure/

Great article!


From article in the link above:

GM says the integrity of the coolant is dependent upon the quality of the antifreeze and water. If poor quality water is used with Dex-Cool, it may cause problems. So GM recommends using distilled or de-ionized water with Dex-Cool.

don't mix it with tap water

uh ohhhh........

 

[ChaseDE]

when i had my cadillac i was glued to the cadillacforums and those guy, experts in the field, made sure to stress the importance of using distilled water with your dexcool or you would have problems.

 

[KDXSR5]

I have all GM vehicles in my stable and have for years. I always run the dexcool with distilled water and have never had an issue. One of the vehicles has 306,000 miles on it with no problems from the cooling system. I flush and refill every 5 years.

 

[theoldwizard1]

The important thing with antifreeze is to watch it, ...

19 year old E150, Triton 4.6L V8. I think it has only been "flushed" and refilled by myself 3 times in its life. I use Prestone flush (double the amount because I have a rear heater) and a double rinse. I usually buy plain Prestone green full strength anti-freeze.

I had one mechanic tell me he never saw a see-through remote reservoir tank on any car over 5 years old that clean in his life !

Newer, aluminum block cars, I go with the specific manufactures recommendation.

 

[finn]

I've had three vehicles plug the heater core in less than ten years with ethelyn glycol, two Fords and one GM.

I think it's a maintenance issue, not a chemical formulation issue.

I do know that there were gasket compatibility and life issues with the early oat coolants.

 

[ForceFed70]

My understanding is that Dex-Cool isn't all that bad until it get's exposed to too much oxygen (low coolant levels). Something about the oxygen makes the coolant acidic and acidic coolant eats at engine parts causing sludge, gasket failures, etc.

Keep er full and you should have no problem.

Having said that - I did a complete flush and replaced with the traditional green stuff. I might not get 5+ years out of it, but I'd rather do an extra flush than deal with the other issues.

 

[zebrabeefj40]

Put me in the camp that has no issues with Dex-Cool. Bought my '96 Camaro Z28 new and have used nothing but Dex-Cool for the 178K miles I have on it. Change it out once in a while with fresh Dex-Cool/distilled water and cruise on. I did have a water pump leak slowly for several months before I fixed it - no issues with the coolant doing nasty stuff.

I also had a '97 Grand Am with a 3.1. Intake gaskets failed on that one but lucky for me only leaked to the outside of the motor. I ran it for a month leaking before I could get it fixed - never did see the nasty **** from the Dex-Kill video in that one either. When I changed the heads/head gaskets/intake gaskets (head gaskets looked weak too so I did the whole pile at once) I refilled with fresh Dex-Cool and cruised for at least 50K trouble-free miles (car had 200K when I finally parked it with a failing trans).

From my experience I don't see why Dex-Cool gets a bad rap. It works fine for me...

Nick

 

[CJM8515]

The vehicles that are at about the 12-20 year mark used a slightly different formulation of dex cool than what they use now. Havent seen issues in about 8-10 years for most GM vehicles.

 

[like2wheel]

head gaskets looked weak too

Nick

I gotta ask...
What made you determine that the head gaskets "looked weak"?

 

[bwringer]

In the motorcycle world, there are tons of people who seem to think cars have cast iron engines, and only super-expensive motorcycle-specific antifreeze is suitable for the exotic space-age materials such as aluminum used in their motorcycle engines.

 

[Schurkey]

Does anyone but me remember that Buick, Olds, and Pontiac had aluminum heads, blocks, and timing covers in 1961? Aluminum-compatible antifreeze goes back at least that far.

Has anyone but me noticed that the vehicles that had the worst problems with Dex-Cool were also the vehicles that had the worst problems with intake manifolds or intake manifold gaskets leading to coolant contamination? I think the intake seal goes away, then the coolant gets contaminated with reversion and/or raw fuel. Then the coolant turns to slime.

There is also the issue of defective rad caps (see GM service bulletin) and air entry into the cooling system, but the component with the most air (the overflow bottle) seems to have the least amount of trouble.

I have no problem with Dex-Cool; although it's not my coolant of choice. I tend to use "universal extended-life" products, always with distilled (reverse-osmosis) water.

When I had ordinary green coolant, I could count on it going double the "recommended' service life, with extended life coolants I don't know how long they last because I've never put that many miles or years onto a vehicle that I've flushed the coolant on.

Dex-Cool certainly had a reaction to...something...especially in the first few years. My guess is that they've both improved the formulation, and they've improved the vehicle gaskets and seals to reduce or eliminate the cooling-system problems. I think it's become a non-issue with too many people repeating old information, somewhat like "Deathanol" (Ethanol) in gasoline. I just can't work up the gumption to be worried about it any more.

 

[gungatim]

Dex-cool may be fine in a perfect world, and I'm not really knocking it, it's just that unless you buy the car new, and do your own service, you really have no idea what the previous owner did/used, or the kid at the oil change place when he added to the overflow...

that's why I am in the camp of dump it and replace with regular anti-freeze. there are just too many failure modes out of your control to risk it. air, tap water, mixed with wrong stuff, even the stuff that says compatible with dex-cool AND ethylene glycol--I just don't trust the rules are always followed.

 

[slow]

very possible the coolant gaskets could be part of the issue. I've always owned LS1 and LS2 based vehicles, with dry intake manifolds, and never had an issue.

 

[jimindm]

Dexcool certainly has some issues. I would agree that many of those were in the early days of dexcool.

I always heard that it did not like the air in cooling systems. Something about the air causing something in dexcool to mix into the mud it resulted in.

You could say that it was an issue with the cars prone to intake gasket leaks, but I think the intake gasket leaks, just from not staying full of antifreeze, contributed a lot to it.

I would also agree that the plain old antifreeze was good for so long, why not keep using it. There were many aluminum parts years ago, and it seemed to work fine.

One of the things I always heard, was GM knew the formulation of the dexcool was a problem in certain situations. When they decided to roll it out in production, they signed such contract that they had to buy so much of it. While many of the problems associated with it did not surface until long after the vehicle was out of warranty.

If you remember most dealers only wanted to work on warranty stuff, they did not chase customer pay like they do now. Some of that started to change after dexcool was out for a while. It was hard for the manufacturer to claim in was customer neglect, when they had serviced some of the problem ones, all along.

 

[BearsFan315]

own a 97 sunfire 200k+ miles, and a 01 saturn with 250k+ miles

both dex-cool, flush and fills and never an issue, no sludge, no grudge.

 

[zebrabeefj40]

I gotta ask...
What made you determine that the head gaskets "looked weak"?

When you can see the edge of the gasket delaminating around the edges of the head. Likely would have started leaking coolant at the head gaskets next. Further, I bought the Grand Am because I had a parts car. Said parts car had just had all the other coolant leaks fixed only to blow head gaskets. Since I'm already most of the way to the head gasket while swapping the intake gaskets it made sense to me to just go the rest of the way. I didn't want to go back into the motor again in a month to deal with blown head gaskets. Once I had the heads off I could see more weak places in the gaskets. I also found one of the exhaust valves had cracked in half so in the end I needed to be there anyway.

Nick

 

[SARG]

Gotta join the choir on this issue. Got a 07 Impala that failed to provide heat a month ago.
Took it to the garage and the mechanic knew what the problem was immediately. He flushed the system & replaced the coolant with the Prestone stating the Dex-Cool is a notorious problem.

 

[finn]

The early sixties GM 215 V8 engines, along with the AMC six and the aluminum versions of the Chrysler slant six all suffered from horrendous cooling jacket corrosion when using the ethelyn glycol available at the time, contrary to previous posts on the subject.

The junkyards were full of unusable aluminum engines back in the late sixties and early seventies, all with corroded water jackets.

 

[chris142]

I work at a radiator shop. Dexcool works fine when the car has a pressurized bottle. If the car has a cap on the radiator Dexcool is not a good product to use.

 

[SMKS]

I work at a radiator shop. Dexcool works fine when the car has a pressurized bottle. If the car has a cap on the radiator Dexcool is not a good product to use.

I've read this same info other places, too.

Hey OP, the Dexcool hate is overblown. There may have been some problems in isolated situations, but in most cases it works fine.

Don't worry about it.

 

[import extermination]

Dexcool is fine. But after the 5 year mark, it starts to sludge up and eat all sorts of goodies ( iv seen head gaskets, aluminum heater hose fittings, some bad cases even heads.).. so as long as you flushed out the old stuff. The new dexcool you put in will br fine. Just dont mix it with other types

 

[wagzilla]

Fun fact Dex cool does not wash out your bearings when it mixes with your oil the green stuff does, just something to think about.

James

 

[pancho400cid]

Appreciate all the input guys. I was really oblivious to the whole back story.

The Saturn has a pressurized overflow reservoir. I did not use de-ionized water and did not flush out the system to any degree other than draining and then refilling after the work was done. I had put green "universal" (mixable with any color - so the label claimed) stuff in back when it was leaking just to keep the level up.

All in all... I'd say my coolant situation is not good. I am sick of working on the beater for now. I'd rather spend some of the precious little free time on a more fun project. I will probably flush and re-fill within the year though. This time I'll be a wiser man thanks to the info here. Not sure if I'll keep the Dex Cool or "go green". That car is most definitely not "over-maintained" LOL. If I go with Dex cool the second time it will be with a thorough flush and D/I water (easy to get if you buy 50/50 premix I guess).

 

[slip knot]

My 98 went into the stealership 2000ish. They stated that the Dexcool plugged the radiator due to the leaking manifold gaskets causing air to get in the system. I was WTF? went by my favorite radiator shop and they stated the same thing. Switched to the green then and have never looked back.

 

[Schurkey]

I had put green "universal" (mixable with any color - so the label claimed) stuff in back when it was leaking just to keep the level up.

Better than nothing.

Not sure if I'll keep the Dex Cool or "go green". That car is most definitely not "over-maintained" LOL. If I go with Dex cool the second time it will be with a thorough flush and D/I water (easy to get if you buy 50/50 premix I guess).

1. You have other choices than just "green" and "DexCool".
2. Premixed coolant is a consumer cheat, it's hardly less expensive than pure antifreeze, and a bottle of distilled/Reverse Osmosis water is under a dollar at any grocery store.
3. Lots of engines have frozen and cracked because the flush-water wasn't properly drained; and the resulting antifreeze mix was substantially weaker than what was intended. Many (not all) engines have block drain plug(s) than can be removed to drain the bottom-half of the water jacket.

 

[justanengineer]

The biggest issue with Dexcool I've seen or heard about was simply that lubies 20 years ago would mix the two, either by topping off a Dexcool filled vehicle with EG or by selling customers a radiator flush and refilled with EG which then mixed with the Dex left in the engine. For my personal GM vehicles I've always used Dex if it had Dex in it, only flush every 10-15 years and never had an issue.