jarnold

Replacing my Radiator in my 20 year old C5. Leaking. I have read a lot about how Dex-Cool is not good. So while I am dumping most of it should I go ahead and covert the old Prestone type? Is the new Dex better. Car has only 66k on it and the Dex looks good still. I am the 3rd owner and do not know if it has been Flushed before. I hope it has.

If the consensus is yes, what is the best procedure to flush it as they say you have to get all of it out. GM flush product?

One other thing. The new radiator has the Coolant ports and was told you can use the Automatic Radiator with the manual cars. Should I just plug the ports? Was told I could use brass plugs and drill a small whole to vent them or something?

Velocity_Vette

I agree with above that you probably really want to check the system thoroughly. I recently had a leak and thought it was possible the top plastic portion that had cracked in the radiator but it actually ended up being the upper hose. A quick pressure test confirmed this. I ended up replacing all the rubber hoses (ordered them from Cultrag) and installing new clamps. Indeed it's not to doubt your work, but I was able to spend much less rather than spend $200+ on a radiator (and then not get the automatic one like you did for my manual trans car).

I re-filled with Dex-Cool; did not see a reason to go to standard coolant. Indeed per above if you go with "normal" coolant you have to ensure that the system is completely flushed. Usually one flush is not going to get it all out. If any significant amount of Dex-Cool mixes with normal coolant it will cause issues. Honestly that's likely the reason why Dex-Cool get the rap it does; owners improper serving their cooling system.

The other thing with replacing with "normal" coolant is it has a shorter service life than Dex-Cool, so you would need to take it into consideration. Proper Dex-Cool in a well-maintained system has a longer service life.

KCK8766

Out of curiosity, what are the "issues" that could occur with mixed coolant types?

StrangelovesM6Vert

Jello plugging up your cooling system

El original

Curious what OP heard about Dex cool that is not so good?

Macleod52

I know back in the early and mid 2000's people were complaining because it would turn brown. People freaked out and there was a class action lawsuit I believe. GM is still using dex-cool so if there was something inherently wrong with it they would have stopped using it by now.

Bill Dearborn

When GM first introduced it in the mid 90s on some of the V6 and V8 engines there was a problem with it eating seals. That problem never occurred with the LS1 engines it was all the old style engines that were designed 40 or 50 years before. I have had Dex in my cars since 1997 and it is fantastic compared to the old crappy green stuff that HAD to be changed out every two years.

My 97 went through 5 years of he original Dex and then I changed it according to schedule and it went another year before I sold the car. The next owner drove it for several more years. Same for my 03Z and 03 Tahoe which I still have. It has had the coolant changed every 5 years since I purchased it. 110K miles and still on the original water pump, hoses and radiator. The DexCool Coolant is scheduled for another change in early 2018. My wife's 99 Saturn went 5 years between changes and was still providing service without any cooling system issues up until last year when he and his wife sold the car. My 08 Malibu went through a 5 year change and my Grandson who owns the car now is planning on changing the coolant next year. What amazes me is how after 5 years the coolant looks the same as when it was put into the engine.

Bill

Rob 02

I used Dexcool after my rebuild which is available almost anywhere and good enough.
There's some new technology now in the coolant market. Some of the new coolants can go 10 years or 150,000 miles.

I wouldn't recommend the old school stuff. The coolant path on this car is almost completely made of aluminum whereas the old ones were almost all iron. The coolants have anti-corrosive properties for use in certain applications.

I do remember reading about the Dexcool law suits. I haven't heard of people having problems recently so I am assuming the problems with it have been addressed (I could be wrong). Apparently if air was in the system, the coolant could foam up and break down into a sludge. I also heard of it having damaging the water pump seal in the past.

coupeguy2001

I read about ten years ago, they reformulated it and the issues with it are gone.
Now, any coolant you buy is a standard formula, and can be mixed with any coolant. Next time you are in an auto parts store, pick up a jug of coolant and read the back label. Any coolant that's produced today can be mixed. any color, anyway.
Just be sure it is a 50/50 mix with water.
Straight coolant will not cool as well as straight water.
The coolant mix gives the best of both worlds.
add coolant, raise the boiling point. add water, and that cools because it wicks away the heat.
Add a radiator cap (or pressure cap) and the boiling point goes up 3 degrees for every pound on the pressure cap.
so 15 Lb cap adds 45 more degrees of temperature before the water boils.
Boiling water is not good.

Vetteman Jack

I personally would go back with Dex-Cool. I've had it in many cars and it has never given me any problems. I do change it out at the normal recommended intervals.

Bill Dearborn

Dexcool is a different chemical formulation that the Green Stuff and the two do not react well together. A lot of the problems came from gaskets that didn't hold up to DexCool and due to owners mixing fluids or not performing proper cooling system operation.

Copied from another location on the web:
Here’s the REAL scoop on Dex-Cool and coolants in general.


First some history

Most of the older green coolants were silicate based. Their primary job was to prevent freezing. But they also had additives to prevent corrosion. In the case of the green coolants, the silicates deposit on metal surfaces to “PASSIVATE” them. In other words, the silicate coats the metal parts to prevent electrolysis. The problem with silicate is that it’s abrasive, so it’s tough on water pump seals. Plus, green coolant doesn’t have a long life—-max 2-years or 24,000 miles. When car makers switched to aluminum engines and radiators and away from cast iron components, they also switched to long-life coolants. The old rule was that you could add the newer coolants to the old green stuff and all you did was reduce the life of the long-life coolant to that of the old green stuff. Well, history has proven that theory wrong. You CANNOT mix coolants at all (More on that later>

The Dex-Cool Lawsuit

So GM switch to organic acid technology (OAT) and named that orange coolant Dex-Cool. And, they gave it a 5-year, 100,000 mile lifespan. At the same time, GM also started using plastic intake manifold gaskets with a silicone bead around the ports. For some reason (and NO ONE agrees on why this happens) the gasket material and Dex-Cool interact with one another, causing leaks. The problem was so extensive that it affects just about every 3.1 and 3.4-liter made in the late ‘90’1 and early 2000’s. The repair involves pulling the intake manifold and replacing the gaskets with a re-designed style. At the time, many shop re-used the old intake manifold bolts with the new gaskets and then re-installed DexCool, only to see the gaskets fail again. So they blamed DexCool. Wrong!
The problem with these gaskets is that they’re fairly low torque (because they’re plastic). So if you don’t use new bolts and follow the torque directions TO THE LETTER, you’re going to get another leak.
Bottom line is that owners sued GM in a class action and won a settlement to reimburse them for the gasket failures.

So it’s true that DexCool caused gasket leaks, but the real problem was incompatibility between the plastic and the coolant. Everyone assumes the problem was Dex-Cool, when in fact, the problem was the type of gasket material combined with the use of Dex-Cool. GM has redesigned the gaskets that the problem has now been fixed. GM still uses Dex-Cool coolant and there is no longer a problem with gasket coolant interaction. So contrary to the ranting, DexCool IS the recommended coolant for GM engine.

Other DexCool problems

Shops reported other problems with DexCool engines besides the 3.1 and 3.4-liter engine. Specifically, shops reported sludge buildup, especially in cast iron engines. But after a thorough investigation, it turns out that the only time sludge builds up is if the engine is low on coolant. When engines run low on coolant, the organic acid technologies oxidize and cause iron oxide deposits. The “rusting” usually NOT affect newer aluminum engines. But, running ANY engine when it’s low on organic acid type coolant cause form sludge.


Enter the new coolants

After GM came out with Dex-Cool, ALL the car makers jumped onto the reformulation bandwagon. Honda came out with a blue low-silicate formula. Others adopted a Hybrid Organic Acid Technology (HOAT). And each company formulated their coolants to work with the types of metals, gaskets, and seals used in each particular engine. The current situation is that you cannot even use a single coolant for an entire manufacturer’s lineup. Ford has several different coolants and you must use the correct coolant in each engine, simply because every engine has a different combination of seals and plastic materials.


Universal coolant? Ba-humbug

The big name coolant manufacturers felt left out of this game and somebody had to make a coolant that could be sold at retail auto parts stores. So the big name brands came out with “universal coolants.” Yeah, guess what? There’s no such thing. I’m not aware of a single car maker that condones the use of a universal coolant in all of their models and engines.

Mixing coolants becomes a HUGE no-no

Remember I talked about the old theory that it was ok to mix coolants? Well, time has proven that theory wrong. Mixing different coolant formulas is a prescription for big time trouble. In fact, Gates (the belt and water pump manufacturer) recently issued a service bulletin warning auto repair shops that their water pump warranties are null and void if the shop uses the wrong coolant or mixes coolants. Gates has seen water pump failures in as short as 7 days, although most other failures won’t show up for a long time. But if you mix coolants, or use the wrong coolant an get a leak or clogged heater core down the road, who’s going to suspect it’s the fault of the coolant.

Bottom line

If someone tells you to use a coolant OTHER than the one recommended by the car maker, DON’T listen. If you have an extended warranty, you will void it. Even if you don’t, you risk major damage. Most engines take less than 2-gallons. Dealer coolant will cost an extra $10/gallon. Why risk engine, radiator, heater core, gasket, water pump, heater tubing, and seal failure to save a lousy $20?

Dexcool was originally a Texaco Zerex product that GM had exclusive rights to use. Then sometime in the 2000s the Texaco Zerex brand disappeared from shelves and several other companies started making the DexCool formula.

Bill

UstaB-GS549

FWIW, my 45k mile 2002 has original Dexcool in it.... I keep meaning to get around to changing it..... it's still pink

Rob 02

Interesting write-up Bill.

So the formula hasn't changed and it is still the recommended coolant for this engine?