: Antifreeze?

12-26-06, 11:49 AM
I was thinking swapping my LT1 water pump this week and now I am wondering what Antifreeze to use. It got me wondering when at http://impalassforum.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=33;t=004863 they thread starter said he only uses the Toyota red antifreeze.

In my experience, every Toyota I have ever pulled the radiator cap was ALWAYS clear and you could see 6-10 inches down in the radiator and the coolant resovoir was always clear and radiator corrosion free. So it makes me wonder if that is a good investment to keep my LT1 cooling system up to snuff. GM/Ford/ChryCo have always had corrosion issues in time. Toyota doesn't appear to have these issues. Is this key to keeping an LT1 waterpump living longer? Toyota claims that using silicate based antifreeze will cause seal issues, which is what GM has issues with on the Opti. Worth the $20 a gallon???

I just found this at: http://www.automotiveforums.com/vbulletin/t299528.html

Some good info. Bottom line use Toyota (OEM) red to protect metal and seals. Use de-mineralised or distilled water. Minerals dissolve into scale that clings to metal and clogs radiator passages.
There are currently five main types of antifreeze. In all cases the 'anti-freeze' properties last the life of the coolant - it is the various additives that deteriorate with time. These additives include anti-foaming agents, surfactants (to improve the 'wetting' of the coolant and hence give better heat transfer) and anti-corrosion additives.

1. Ethylene Glycol - this is the traditional stuff, used since the 1950's. It uses silicates to stop corrosion by passivating the metal surface. This type of anti-freeze is suitable for most European cars, but not Japanese cars. Japanese manufacturers normally recommend a low- or no-silicate formulation due to the nature of the seal materials that they use (see below).
Typical service life of 2-4 years.

2. Ethylene Glycol: Low or no-silicate formulation. This is specified by most Japanese cars. OEM Nissan, Toyota 'red' etc. antifreezes use phosphates rather than silicates to inhibit corrosion. Silicates are abrasive and the use of high silicate antifreezes in Japanese cars may result in premature failure of seal materials.
Typical service life of 2-4 years.

3. Mono Propylene Glycol - this still uses silicates and is claimed to last 4 years. Mono Propylene Glycol does not conduct heat as well as Ethylene Glycol and currently carries NO recommendation from any major car manufacturer- and some actually caution against it. The main claim to fame for Mono Propylene Glycol is that its less toxic than Ethylene Glycol.
Typical service life of 2-4 years.

4. Organic Acid Technology (OAT) - e.g. GM 'DexCool'. Introduced in 1995, this is a recyclable and biodegradable antifreeze which is based on organic acids and is silicate- and phosphate-free. However, due to the nature of the chemicals used, it can attack certain seal and gasket materials and therefore should only be used in vehicles for which it is factory specified.
OAT antifreeze MUST NOT be mixed with the types listed above - if you wish to switch to OAT type then the cooling system must first be chemically flushed.
The claimed service life of the corrosion inhibitor package is about 5 years, or 100-150,000 miles.

5. Ethylene Glycol-based 'Hybrid Organic Acid Technology' (HOAT). Uses Ethylene Glycol, but with OAT-based corrosion inhibitors and some added silicates; most usually BASF's "Glysantin" additive package is used (also known as 'G-05'). HOAT is less agressive than straight OAT anti-freeze and has better cavitation resistance. Halfords 'Advanced Antifreeze' is an HOAT formulation. Again, best to thoroughly flush your system if switching to it.
Lasts 4-5 years.

The bottom line is to refill your engine with what the factory supplied and do a flush-and-refill every 4 years maximum. If you have a Japanese car, stick to the maker's brand since non-OEM coolants may contain higher levels of potentially damaging silicates.

If mixing your coolant from a 'concentrate' then use demineralised or distilled water. Tap water often has a lot of dissolved minerals in it which can leave scale deposits inside the engine's coolant passages.

12-26-06, 12:39 PM
Whoops!?! I used the green stuff in my car because I have heard from several people that Dexcool builds up and does not work after awhile. I just replaced the water pump in my car for the second time (First one was a reman that leaked right away) in a month and used green stuff both times. Works fine for now. Added Redline Water Wetter. Temp with factory temp thermostat rarely gets above 173 when driving normally. I hope the green stuff doesn't ruin the internals?!? :hmm:

12-26-06, 01:02 PM
Not at all, actually I haven't been able to find the non extended life stuff at all anymore. Look around, it is rare if you CAN find it. So you are running the right stuff. Remember, the 94 came with old stuff, I think 95-97 LT1's had the new stuff. Identical parts, so it won't hurt anything...

Best to use distilled water as it will keep the hard water deposits down, so the lime and scale will be minimized.

12-26-06, 04:31 PM
I wouldn't use anything but the same type of coolant that came with the vehicle from the factory. Oil is alright to switch, but if you're replacing your waterpump with another factory unit, then I'd stick with the same stuff you've been using. My radiator looks exactly how you described Toyota's you've seen; I'll have had my Brougham 2 years to the day tomorrow, and I've changed the coolant once, when I put a new waterpump in last summer. I only use the 50/50 stuff. That way I know it's exactly mixed and that I'm not putting a single speck of mineral or anything in my engine.

12-26-06, 04:39 PM
Amen to that above.
Not knowing what had been done to my 1995 FWB regarding the cooling system, and seeing that the heater didn't (!) on the first cool day here in CT, I remembered the posts on flushing the heater core using municipal water pressure and Ye Olde Garden Hose.
Afterwards, with much flushing of fresh city water and drain, drain, drain, all openings were closed and DexCool and distilled water went in, along with two of those GM veggie pellets - properly ground up, of course - and the car seems happy as a clam.
Oh, yes. I also made sure to let the car burp through the bleeder atop the waterpump, expelling all the air bubbles in the system.

12-26-06, 05:10 PM
I have the Walmart ext life coolant now to put in (I have no idea what is in it), it needs to be swapped (coolant test strips show it not in good shape) anyway, so I will do it with the waterpump swap I am going to try to do this week.

I will mod my water pump so it can't ever leak on to my Opti and try to come up with something to protect the Opti from water draining on it from anywhere else. And seal the Opti with permatex to make it water proof.

Not sure if I buy that stock coolant is best, stock is also a comprimise of cost and performance. Add $4 a gallon to every car on the production line and you understand why this is an issue to GM/Ford/ChryCo.

We'll see, its cost may be too much for me too. I have heard $20 a gallon..... Owch....

12-26-06, 08:44 PM
$19.95/Gallon at AutoZone last fall, here in West Hartford for DexCool.
Anybody find any better price at something like CostCo, Sam's or WalMart?
BTW I had to replace my wife's distilled H20 she uses in her steam iron.:tisk:

12-26-06, 09:53 PM
$20/gal for DEXCOOL??? It is only like $9 at walmart! Owch!

12-27-06, 01:19 PM
NAPA has fair pricing on dexcool - last time I bought it was $6 or so? I use it in my Caprice because it had it from the factory, and has low mileage. Dexcool, like the opti on the LT1 engines, unfairly got a bad reputation IMO.
It is the PELLETS added at the factory that cause problems, not the Dexcool itself. The pellets/tablets were added to detect leaks or something; irregardless, they collect in clumps and can choke off water passages.

So if you have factory Decool then I would highly recommend flushing the system completely. But since the cars are all pretty old now, chances are you've already had problems and flushed anyway. Or, since it is good for 100K miles or five years then most likely it has been at least drained out already.

One thing to remember is that mixing Dexcool with green standard coolant nulifies the benefits of Dexcool. So the 5 years you get with Dexcool is reduced to one year intervals of use once you add in the green stuff. SO be sure to drain all of the old coolant out if you plan to use Dexcool.... on LT1 cars this would involve removing the knock sensors in the block.

---FYI my Caddy uses the green stuff. That's what it had from the factory and also when I bought the car. To me it is not worth the hassle and brain-racking to remove all green coolant and add in Dexcool. I added a coolant gauge so I can keep a close eye on everything and so far I am plenty happy.

12-27-06, 01:49 PM
the battle goes on. I pretty much am going to stick with whatever factory serves up. For me it happens to be dex cool.

12-27-06, 04:51 PM
I used the new Prestone antifreeze/coolant that can be used with Dexcool. It is green.

12-27-06, 05:20 PM
Look closely at the bottles in the store, you are hard pressed to find NON extended life coolant. Even the cheap Walmart stuff is DexCool compatible now.

Color is meaningless anymore....

I called Toyota, $20 a gallon is confirmed.... Not sure I want to pay that...

12-27-06, 10:01 PM
Seeing that Tom saw DexCool for $6.00/gallon, pardon me while I go :banghead:

12-27-06, 10:02 PM
Looks like I got it without even a KISS ! :annoyed:

12-27-06, 10:10 PM
Got your receipt? Find the cheapest you can, buy it and return it to the other store where it was higher price.

12-28-06, 12:58 PM
Wotta great idea!
Now I can't remember if AutoZone put tape stickers on the bottles or not like Sears does.
Gonna have to do some thinking. And for nearly $28.00 bucks, it's worth it! :hide:

12-29-06, 02:12 AM
I went to Walmart tonight to double check, the stuff I saw isn't Dexcool, it is "Dexcool approved". Prestone stuff. Probably close enough. $9.80 a gal. Walmart noname stuff is $6.80 a gal. That is the range of prices for antifreeze there. Walmart doesn't appear to carry the real Dexcool anymore....

12-29-06, 08:56 AM
I Have seen remarkable results with MB-coolant, In a 25 year old MB 300SD with a bazilion miles being rebuilt. the freeze plugs were still shiny.

12-29-06, 06:13 PM
Well, got my water pump off, but still can't get the harmonic balancer off the hub to inspect the Opti. Well, at least I don't have an original Opti (I am soooo glad!), it has a date code of 2002 or 2003 on it. But I still want to pull the cap off and inspect it. Bought the inverted Torx socket from the local Snap dealer for $14.05. Soon as I get the balancer off the Opti will come apart and I can swap the water pump drive seal too.

Johnny Bravo
12-31-06, 02:51 AM
It is the PELLETS added at the factory that cause problems, not the Dexcool itself. The pellets/tablets were added to detect leaks or something; irregardless, they collect in clumps and can choke off water passages.
GM stopped adding pellets to the cooling systems years ago. Furthermore, Dexcool, (aka "deathcool"), was, and is, the problem. That stuff caused us an $800 repair job at 56,000 miles on a 1999 Monte Carlo. It ruined the intake manifold gasket, radiator and mucked up the whole cooling system.
In fact, there is a class action lawsuit in progress against GM regarding Dexcool.:mad:
Use at your own risk.

The good old green Texaco antifreeze works just fine, thank you very much and it's low silicate. Flush it every two years, or 30,000 miles and the cooling system will probably outlast the car.

12-31-06, 08:40 AM
Get me the reference for that lawsuit so I can dump the coolant in my FWB and get rid of the veggie pellets.
(I always wondered how ground up Ginger could do any good in a motor.)
But how could Dexcool mess up manifold gaskets?

12-31-06, 09:05 AM
Dexcool wasn't, and isn't the problem.
There are other factors at play here.
If Dexcool was so awful as everyone claims it is it wouldn't still be in production cars 10 years later. BTW, I have seen cooling systems with, and without dexcool that would make you vomit and it was from other factors.
There is no evidence outside of speculation to indicate that Dexcool is the ACTUAL CAUSE of these failures. A class action lawsuit from a bunch of individuals with an axe to grind is proof of nothing. Let's see the documentation of the controlled study where they indicated that the cause of the failure was simply having Dexcool installed, then I'll take your word for it.

Also, if that engine was a 3100 the gasket was the problem, not the coolant.

12-31-06, 09:26 AM
I just came back from Googling up all sorts of "DexCool Lawsuits" items and there are literally hundreds of claims from people hollering their heads off about DexCool.
>I will admit that when I had a No-Heat situation with my 1995 Cadillac Fleetwood Brougham, I did what was recommended on this BB and took off the two small hoses coming from the water pump and flushed the heater core.
The most GawdAwful gook you ever saw came out when I let garden hose pressure blast that garbage out of the heater core - slowly at first - and then reverse flushed and got even more.
I believe it was those vegetable pellets that were clogging the core rather than anything to do with DexCool, but I have no way of proving it.
Then I flushed the rest of the cooling system with city water and drained it completely.
After that, I reconnected all lines, shut off all drains and stole my wife's distilled water (for her steam iron) and then installed 2 gallons of DexCool, in effect making a 50/50 mix along with 2 (not 3 or 4 as recommended) of the veggie pellets.
That was in early September and I have adequate heat, no discernible coolant loss and all seems well in the radiator department.
So I'm beginning to wonder . . .
Is this another bunch of Ralph Nader shit like the stuff about the Corvair?
(Yeah, I used to race the little Yenko-equipped beasties and I have the trophies to prove it!)

12-31-06, 01:46 PM
These DexCool death stories.... iron heads? I remember hearing somewhere that had something to do with it. Something about internal surface rust occuring with an air pocket, then getting washed away and the rust gets suspended in the coolant. Considering the biggest issues were the 4.3 S-Trucks, and that Monte depending on that the problem was (the 60 deg V6 gasket problems.... not coolant related or if it came with the 3.8, iron heads) it sounds plausable.

Color may be meaningless anymore, but theres still a few varieties im not sure what category they fit into. I know what the orange DexCool is, and Toyota's red... But VW/Audi pink, Euro blue, and Ford yellow i'm still not sure about.

Johnny Bravo
01-01-07, 01:05 AM
Dexcool wasn't, and isn't the problem.
There are other factors at play here.
If Dexcool was so awful as everyone claims it is it wouldn't still be in production cars 10 years later.
The main problem was the Dexcool had turned into thick brown sludge at 56,000 miles, (3.1 engine aluminum heads). The mechanic said he has seen the same thing on other Dexcooled vehicles, and worse.

Fortunately, I caught it before any serious damage was done, others aren't so lucky, and don't realize a problem exists until the car overheats. My girlfriend has a 1995 Olds Cutlass she bought new with the same 3.1 engine, however, it had the green coolant, (last year at GM). It has over 140,000 miles with no cooling system problems at all, original hoses and everything.

There is no denying there is a problem Dexcool, be it air contamination, low coolant levels, whatever. Simply because GM continues to use it doesn't mean all is well.:helpless:

There have been many engineering issues that manufacturers have choosen to ignore or deny for years such as; Toyota engine oil sludge, GM piston slap, Cadillac Northstar oil consumption, and exploding fuel tanks on the Ford Crown Victoria, just to name a few of the more recent ones.

01-01-07, 12:30 PM
Sure can't deny manufacturers denying really bad problems with their products:
>Ford Pinto: Save $15.00 per car by not shielding gas tank said the bean counters. We know where that went.
>Ford Crown Vic: Make fewer welds where the rear main panel meets the floor pan: Result = rear end collision results in flaming gas tank inside the car. At least two cops burned alive. More civilians toasted, too. Fully documented at ALLPAR.COM under their cop car sub site where they note how Dodge put so many spot welds in their cop cars that the dealers hated to repair them after a wreck.
>Ford with the transmissions slipping into gear from PARK. The company I worked for send out bulletins after a company Lincoln backed over a chauffeur who had taken a bigwig to the airport and was unloading luggage, got pinned between the car behind the Lincoln. My company had nearly 1,000 Fords in the fleet and we had to take all of them back to the dealers across the USA.
>Ford, AGAIN with brittle steel in the engine fuel lines permitting them to crack and spray fuel over a hot engine causing fires. More bulletins to company car drivers.
While we're at it, I'll admit I'm a Corvair fan. Nader NEVER won a single suit against GM, despite the publicity, but perception is reality to the public.
>Dodge had more than its share of trouble with the V-6 with oil galleries too small. If oil wasn't changed regularly or the oil was lousy in quality, the engines crapped out at about 60,000 miles.
This one sounds like the HT 4100, doesn't it?
Does anybody know it the same engine designers who worked at GM migrated to Chrysler and did their dirty work on that infamous Dodge motor?
Anyhow, Chryco had many law suits.
>Chrysler, Plymouth, Dodge, 4 cylinder motors with failing head gaskets.
This one hit us personally - The primary problem was so stupid it was sickening! One headbolt was too effin' LONG! Thus the head could not be torqued down properly. Thus, after a variable length of time, the head gasket blew. There was a "secret" recall. Our dealer tried to scam us but we had bought an extended warranty and made them fix it after 3 years.
That $1,000.00 warranty paid for the $1,700.00 fix !

So I really have to wonder what the REAL story is with DexCool:
>DexCool actually destroying the engine internals?

I wish I knew, since the stuff is inside my LT-1 and may be gnawing at its innards.

01-01-07, 04:12 PM
Get me the reference for that lawsuit so I can dump the coolant in my FWB and get rid of the veggie pellets.
(I always wondered how ground up Ginger could do any good in a motor.)
But how could Dexcool mess up manifold gaskets?

Dexcool can't mess up the intake gaskets in an LT1, which is the motor my original comments were aimed towards. Coolant doesn't pass through the intake manifold in an LT1 as it does in other SBCs.

The LT1 Impala/Caprice crowd pretty much regards the pellets as the root cause of mucking up of the cooling system. Dexcool in itself, as pointed out by another poster, is fine since it is still used today.

01-01-07, 08:43 PM
I flushed out my block, heater core and radiator today and refilled with tap water (all I had on hand) and Walmart ext life coolant.

I haven't put in pellets or anything else. So leave it alone?

01-01-07, 09:11 PM
If you live in Milwaukee or the nearby area, that tap water came from Lake Michigan and is heavily chlorinated. Tasted yucky, but the area never suffered from drought!
Heck, when we lived there, the sprinklers were watering the grassy islands in the middle of Capitol Drive during one of the worst droughts in the midwest in years!
Here in Central CT, the water is unusually good and free of minerals but chlorinated and fluoridated. Tastes great but that latter combination would make me edgy when heated in a cooling system and H2F (even a little bit) might be produced.

01-01-07, 09:13 PM
I am in Darien, we get water out of a local well. And the water I put in is going through the water softener too. So I hope it is ok to use softened water in the cooling system. Definately not a clorination problem here.

Can't say I would want to drink Lake MI water! Milwaukee pollutes it like crazy....

01-01-07, 09:40 PM
Scratching my bald dome, trying to remember about water softeners, I believe there is ion exchange with what you get is the NA ion in exchange for all the other minerals.
Therefore, a bit of sodium should be the lesser of any evils since it would be the sacrificial anode. Wouldn''t it?
Of course you sure as hell wouldn't want the stuff in a battery, but in a cooling system, I'm wracking my brain to try to find something wrong with it and coming up with a blank!
Any chemistry professors or chemical engineers on the board? (I'm part civil, part mechanical, ALL RETIRED! :cloud9: I even surrendered my shingle since I didn't want to go back to school the required # of hours to keep up my license! Lazy, Yeah!)

01-02-07, 12:14 AM
Anyone? I hope I didn't ruin 2 gallons of antifreeze....

Nor this: http://www.peakantifreeze.com/faq.html#B

Peak says no....

"B. Can I mix ordinary tap water with antifreeze?
Yes, tap water is commonly used for mixing with antifreeze, however, deionized water or distilled water is preferred. Do not use water softened with salts to mix with antifreeze. "

http://www.babcox.com/editorial/tr/tr110046.htm This isn't comfort reading....

Under The Cap, Larry Carley, Tire Review, November 2000

Today's Coolant Options Require Close Attention, Different Techniques

When you open a radiator cap these days, you're never quite sure what you're going to find. Antifreeze chemistry has undergone some significant changes in recent years, and the familiar green antifreeze long used in most vehicles is being replaced with a spectrum of not-so-familiar antifreezes that range in color from red to orange to pink to blue.

So it's important to know what type of antifreeze is in the system so you can add a compatible coolant, or replace it with one that provides equivalent or better protection.

Ethylene Glycol
Ethylene glycol (EG) has been the main ingredient in almost all automotive antifreezes for many years, and will continue to be for the foreseeable future. Straight ethylene glycol freezes at about 8° F, boils at 330° F, and carries heat about 15% less efficiently than water. But when mixed in equal parts with water, it creates a coolant well-suited to year-round driving for most applications.

The recommended 50/50 mixture of EG and water provides freezing protection down to -34° F and boilover protection to 265° F in a radiator with a 15 psi cap. If the proportion of antifreeze to water is increased to 70% EG and 30% water, the freezing point drops to -84° F and the boiling temperature goes up to 276° F. Mixtures greater than 70/30 are not recommended because the coolant's ability to carry heat declines as the proportion of antifreeze increases.

Straight EG antifreeze should never be used in an engine because it may allow the engine to overheat. Likewise, straight water should never be used because it provides no freezing, boiling or corrosion protection.

Propylene Glycol
Another base ingredient that is used in place of EG in some aftermarket antifreezes (like Prestone's LowTox and Safe Brands' Sierra antifreeze) today is propylene glycol (PG). The coolant's thermal characteristics are similar to those for EG: a 50/50 mixture of PG and water provides freezing protection down to -26° F and boilover protection to 256° F. If the coolant mixture is increased to 60/40, coolant freezing protection goes down to -54° F.

The main advantage of PG compared to EG, however, is that it is considered nontoxic to animals. That doesn't mean it is safe to drink, but it greatly reduces the risk of poisoning a pet.

Pure PG boils at 370° F and provides freezing protection down to -70° F, so it is sometimes used straight without any water at all as a coolant in racing applications. Running PG straight provides better cooling because there is no water to vaporize in hot areas of the cylinder. This also allows the use of very low pressure or even no pressure cooling systems.

While PG and EG are both compatible and can be intermixed without affecting cooling performance, intermixing the two different antifreezes is not recommended because doing so defeats the reduced toxicity advantages of PG. Also, if a vehicle's cooling system is filled with an extended life EG coolant, adding PG - not currently formulated for extended service - will reduce the service life of the coolant mixture to that of a conventional green coolant.

Intermixing PG and EG antifreeze also makes it impossible to get an accurate indication of the coolant's strength if you're using a hydrometer to check coolant concentration. The specific gravity of EG and PG are different, so a mixture of the two will usually indicate a lower freezing point than the coolant actually provides.

The best way to determine the concentration of PG in uncontaminated coolant (no EG present) is to use a refractometer. The reason is because the specific gravity of PG increases up to about a 70% concentration, then falls off considerably. Consequently, a 100% PG solution will read the same as a 45% solution on a hydrometer.

General Motors and others approve PG as an acceptable replacement coolant, but if making a change it's important to remove all of the old EG coolant before adding PG to the system.

Corrosion Inhibitors
Because coolant is in constant contact with the metal parts of the engine and radiator, some type of corrosion inhibitors must be used in the antifreeze to protect all metal surfaces from electrolysis. That includes cast iron, steel, aluminum, brass, copper and lead solder.

Most conventional antifreezes formulated for the North American market, whether green or yellow in color, contain inorganic salts of borate, phosphate and silicate to prevent rust and corrosion. The additives create an alkaline coolant mixture that typically tests at about 10.5 on a pH scale. The silicates form a protective coating on metal surfaces, and are especially good at protecting aluminum.

To ensure that coolant remains alkaline for a reasonable length of time, there must be enough corrosion inhibitor to neutralize the acids formed from glycol degradation that occurs over time. This neutralizing capability is called "reserve alkalinity," and it varies depending on the type and quantity of additives used in a particular brand of antifreeze.

Heat, dissolved oxygen, minerals in the water, and corrosion inhibitor reactions at the metal surface gradually use up the corrosion inhibitors. And once depleted, the coolant becomes acidic and corrosion accelerates. The secret to preventing internal corrosion, therefore, is to change the coolant before all the reserve alkalinity has been used up.

Periodic coolant changes are especially important with today's bimetal engines and aluminum radiators and heater cores because the different metals create a miniature battery cell that promotes electrolytic corrosion. Aluminum becomes the sacrificial anode, iron the cathode, with the coolant serving as the charge-carrying electrolyte.

The higher the percentage of dissolved minerals and salts in the coolant, the better it conducts electricity and the faster the aluminum is eaten away. As long as the corrosion inhibitors are working, the process is held in check. But once they're used up, corrosion starts to eat away. The most vulnerable components are usually the thinnest, which include the radiator and heater core.

The Effect of Air & Water
Other problems can also accelerate the breakdown of the coolant. An exhaust leak into the cooling system through a cracked head or leaky gasket will quickly destroy reserve alkalinity in the coolant because oxygen reacts with the additives in the antifreeze. If an engine has a leaky head gasket, don't reuse the old antifreeze when the gasket is replaced.

The amount of additive needed to protect the cooling system isn't much - only about 2% to 3% of the total liquid in the jug. This is usually enough to protect for at least two years or 30,000 miles in most vehicle applications - or even longer if the antifreeze is mixed with relatively pure water (distilled or deionized).

Some say ordinary antifreeze can go as long as five years or 100,000 miles before the corrosion inhibitors are fully depleted - provided pure water is used to fill the system, the cooling system was relatively clean when filled (no accumulated rust or scale), and the coolant level is kept full with no air entrapment.

Hard water that contains high amounts of calcium and magnesium can react with phosphates in the additive package to form sediment and scale. That's why European vehicle manufacturers use antifreezes that contain no phosphates (hard water is common in Europe). European antifreeze may be dyed blue, yellow (Mercedes) or pink (VW and Audi).

Tap water in North America also contains calcium, but isn't as hard as European tap water so phosphates are considered okay to use here.

Under no circumstances should softened water be used in a cooling system because softened water substitutes sodium (salt) for calcium. Sodium is very corrosive to all metal surfaces and undermines the corrosion-inhibiting abilities of the additives.

The Japanese and other Asian vehicle manufacturers, by comparison, prefer an additive package that contains phosphates and other inhibitors but no or low silicates. Japanese coolants may be dyed red, but some newer blends are dyed green.

According to the aftermarket antifreeze suppliers we interviewed, using a typical green antifreeze formulated for North American domestic vehicles in European or Japanese vehicles should cause no problems. The basic metallurgy is the same so the degree of protection provided should be the same: two years or 30,000 miles.

OAT Technology
The latest corrosion inhibiting additives are based on a different chemistry called Organic Acid Technology (OAT).

Antifreezes with OAT corrosion inhibitors contain organic acid salts of mono- and dicarboxylic acids such as sebasic and octanoic acids, plus tolytriazole. The coolant is less alkaline and protects with a pH reading of only about 8.3.

Brands with the OAT additive package include Texaco/Havoline's Dex-Cool and Prestone's Extended Life 5/150 antifreeze. OAT coolants contain orange dye to distinguish them from other coolants with conventional additive packages.

The main advantage of OAT technology is extended service life: up to five years or 150,000 miles. But to achieve this length of service, the OAT coolant must not be intermixed with any other type of antifreeze. If the system is topped off with ordinary green antifreeze, the corrosion protection will be reduced to that of a conventional coolant, say the coolant makers.

GM was the first domestic vehicle manufacturer to make the switch to OAT coolants, starting in 1995. Since 1996, all new GM cars and light trucks have been factory-filled with orange Dex-Cool coolant.

GM says Dex-Cool can be used in older vehicles provided the cooling system is first flushed to remove all traces of conventional coolant. But people have said OAT-based coolants do not provide adequate protection for vehicles with lead-soldered copper/brass radiators - a charge the makers of OAT antifreeze say is not true. Texaco/Havoline and Prestone both say their products meet or exceed the ASTM D-2570 standards for corrosion protection.

Sowing OATs
There has been some controversy regarding the use of OAT coolants because of sludging problems GM experienced in some 4.3L S10 truck engines. GM service bulletin #99-06-02-012 says the sludging problem is caused by air pockets in the cooling system from failing to maintain the coolant level or not getting all the air out the system when refilling the cooling system.

GM's fix for the condition is not to switch back to a conventional coolant (which some people advocate), but to flush the system repeatedly until all the brown sludge has been removed. The system can then be refilled a 50/50 mix of Dex-Cool and clean water.

Despite the problems with the 4.3L truck application, the use of OAT antifreeze is expected to grow. DaimlerChrysler introduced its own extended service OAT hybrid coolant for passenger cars in 1998. Unlike Dex-Cool, the DaimlerChrysler coolant contains silicates for extra aluminum protection. DaimlerChrysler, however, does not recommend using their OAT hybrid in older vehicles.

Ford in North America is still using conventional additives in its antifreeze, with the exception of the 1999 and up Mercury Cougar which now uses an OAT coolant. But Ford of Europe has switched over to OAT antifreeze for many of its vehicles. Truck manufacturers including Navistar, Mack and Caterpillar have also approved OAT.

Coolant Checks Important
One problem we have in is that we have no way of knowing what kind of antifreeze is in a customer's cooling system when it comes into the shop. It may be the factory-fill coolant, it may be an aftermarket coolant, it might be a propylene glycol coolant, or it might be a mixture of several different types of coolants.

If you don't keep these possibilities in mind, a simple coolant check with a hydrometer may give you a false indication of the strength of the coolant. A refractometer is a better tool to use because it doesn't measure specific gravity but how the liquid bends light.

Chemical test strips are available to check both the concentration and condition of the coolant, too. But test strips designed for conventional green coolants won't give an accurate indication of the coolant's condition if used with an OAT type of coolant.

Coolant Service Tips
Though most coolant service consists of flush and fill, ethylene glycol coolants can also be recycled using the proper equipment (see sidebar below).

Recycling has obvious environmental benefits, and can be a source of additional profits for your tire store. EG coolants with OAT additives can also be recycled, but the aftermarket additives currently available only return the coolant to a standard two-year/30,000-mile silicate coolant.

When refilling a late model GM vehicle that was factory-filled with Dex-Cool, you have to decide what type of coolant to use. According to GM, Dex-Cool is the only acceptable coolant. But once the vehicle is out of warranty, there's no reason why you can't use another brand of OAT coolant or a conventional EG or PG coolant, say the makers of these products.

The same goes for using an OAT coolant in an older vehicle that contains a conventional green coolant. If the system is thoroughly flushed, you can give your customer the extended service benefits that an OAT coolant provides.

OAT coolants can also be used to refill European and Asian vehicles, provided the system is first flushed to remove all traces of the old coolant.

The National Automobile Radiator Service Association (NARSA), however, is more cautious about the use of OAT coolants. NARSA says OAT coolant should not be used in any Ford product (except the 1999 Cougar) or Chrysler vehicle because there is a risk of water pump cavitation erosion. GM reportedly redesigned its water pumps to eliminate cavitation erosion.

Regardless of what type of coolant is used to refill a cooling system, the system should be cleaned if sediment, rust or scale are present. Also, the system should be pressure tested to make sure there are no leaks. And don't forget to pressure test the radiator cap, and inspect the belts and hoses, too.

Refilling some of today's vehicles can be tricky if the heater core or other hoses are higher than the radiator cap. If the system has bleeder valves, use them. If it doesn't, it may be necessary to jack up the front of the vehicle so the radiator cap is the highest point in the system.

Johnny Bravo
01-02-07, 03:29 AM
Dexcool in itself, as pointed out by another poster, is fine since it is still used today.
Well, some people just have to learn things the hard way I guess. :bigroll:

As for me and mine, (and anyone else with a Dexcool vehicle out of warranty), I'd strongly suggest replacing the Dexcool with a 50/50 mix of old reliable Texaco green antifreeze after a good flushing.

01-02-07, 12:13 PM
Mine will be flushed again soon..... Oh well...

01-02-07, 01:57 PM
Well, some people just have to learn things the hard way I guess. :bigroll:

As for me and mine, (and anyone else with a Dexcool vehicle out of warranty), I'd strongly suggest replacing the Dexcool with a 50/50 mix of old reliable Texaco green antifreeze after a good flushing.

True, one of us will learn the hard way. I have a 96 LT1 Caprice that has 45,000 miles and has only had Dexcool. I stay on top of maintenance (keep all air out of system which the great article above stated is one of MANY factors that can lead to sludge and other problems) and plan to keep the car a very long time. I will find out one day if I have any premature cooling system problems or it will live a long and happy life.

01-02-07, 02:50 PM
I have to question the bit about SODIUM being corrosive in that great article, above.
On the galvanic scale, that doesn't compute. Having had many boats, the usual sacrificial anode, used on rudders, propeller shafts, and inside raw-water cooling systems, is ZINC. You clamp the zinc thingys on to the part you do not want to corrode and the zinc sacrifices itself since it will dissolve in salt or other brackish water before your other precious - and other expensive - metals will be eaten away. Sodium, however, is also 'way down on the galvanic scale while iron is 'way up.
Aluminum isn't all that great, however, but aluminum boats are found all over the place, including in the Coast Guard. But the boats are properly protected either electronically or by use of sacrificial anodes. Also, Aluminum is a helluva lot higher up on the galvanic scale than sodium.
If you want some boaty trivia, stainless steel gets pretty nasty, too, with all sorts of stainless being not so stainless after all in the marine environment. You have to look carefully at the numbers when buying stainless parts for your boat. My happy rule of thumb is; if it's non-magnetic, it's okay. But that isn't always true, either.:crying2:
NOTE ALSO the comment about cooling systems with DexCool needing to be slightly basic (as opposed to acidic).
Those pellets that your GM dealer so happily pushes on you are made of:
That last bit is not our own beloved Big Sal's libations, but is more like a mild Sodium Hydroxide, or chemical to push the pH toward the basic end.
As you may have noticed, most of the ingredients in those pellets are probably in your wife's spice cabinet!

01-02-07, 09:37 PM
Rick 186

I Thought that Sodium is the Oxidizing agent and the metal (zink or aluminium) is the sacrificial anode. The big leap between the two means that there is a large number of ions transferable from one material to the other. The salt itself is capable of being oxidized but much less readily thus being lower on the scale.

I might be wrong...

01-04-07, 10:00 AM
For everybody living in areas with questionable tap water, or on wells (which tend to give hard water), Wal-mart bottled water is $0.66/gal, either distilled or plain whichever you preferr.

01-04-07, 01:07 PM
Pure Sodium metal will IGNITE in the presence of water.
Military uses PHOSPHORUS for even more effect.
This happened in my high school.
The stuff, kept in kerosene, was in blocks about 2"x2"x2". The kerosene was nice and clear and looked like water.
Some smartass switched the kerosene with water in the holding bottle one day and when the chemistry instructor went to add water to the flask holding a block of sodium, the whole thing went off like fireworks, burning him badly. (like in an oil fire, water sinks under the oil)
I wasn't in the class, but in a floor below, in study hall. Big HooRah. Fire trucks, ambulance and the rest of the day off. Teacher out for a month and recovered with facial plastic surgery over the summer. Kid never caught.
Anyhow, sodium is well below Aluminum on the galvanic scale.

I should have said "went to add KEROSENE" and not add water.

01-04-07, 02:08 PM
The local walmarts by me were out of the distilled when I went, they said to try the next day....