Antifreeze: Clearing Up The Coolant Confusion

By Larry Carley c2005

antifreeze coolant

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Antifreeze & coolant related failures are the No. 1 cause of mechanical breakdowns on the highway according to statistics published by the U.S. Department of Transportation. It's not surprising considering how badly most cooling systems are neglected these days.

In April, the Car Care Council offered motorists free vehicle inspections at more than 400 check lanes around the country. The inspections were done to raise public awareness of the council's "Be Car Care Aware" campaign during National Car Care Month. Here's what they found:

The need for cooling system maintenance and repairs are obviously there. But many motorists never check anything under the hood until a problem occurs. Then it's often too late and the damage has already been done.

COOLANT LEAK
An undetected coolant leak or low coolant level can lead to overheating. This can be very damaging, especially in engines with overhead cams and aluminum cylinder heads, because excessive heat causes the cylinder head to swell and distort. This may cause the camshaft to bend, jam or break, or it may crush the head gasket and cause the head gasket to fail. Excessive heat also can cause stress cracks to form in the cylinder head, which may leak coolant into the combustion chambers. Overheating also can cause pistons to scuff, valves to gall and stick, and bearings to seize.

At the very least, a single episode of overheating may damage the thermostat and/or coolant sensor, leading to further trouble down the road if these items are not inspected or replaced after the initial cause of the overheating has been diagnosed and repaired. Simply refilling the cooling system with fresh antifreeze and water is not an acceptable repair for overheating. You must determine why the engine overheated and repair the cause. Treating the symptom (loss of coolant) by adding more coolant may not prevent the engine from overheating again. You need to find and fix the coolant leak.

COOLANT CHANGE
There is a lot of confusion about how often antifreeze should be changed. When the Car Care Council asked motorists how often they thought their cooling system should be flushed, here's the response they received:

Many of these people have probably never read their vehicle owner's manuals and don't have a clue as to how often maintenance is actually needed. These answers would suggest that many motorists over-maintain or under-maintain their cooling systems. The survey did not ask them what they actually did, but from what we have seen, most probably neglect their cooling systems altogether.

The correct answer as to how often coolant needs to be changed depends on the type of antifreze in the vehicle and how much time or mileage has passed since the antifreeze was last changed.

LONG LIFE ANTIFREEZE
Many motorists are under the mistaken impression that today's extended-life antifreeze products are lifetime coolants and never need to be changed. They are NOT lifetime coolants. The recommended replacement interval for most extended-life coolants is every five years or 150,000 miles, whichever comes first (not last). Extended-life antifreeze has been in use for about a decade, and GM has been using Dex-Cool extended-life antifreeze in all of its cars and light trucks since 1996.

With older "conventional" antifreeze products, the recommended replacement interval is usually every two years or 30,000 miles. The same recommendation applies to extended-life coolants that have been contaminated with ordinary coolant. If somebody uses ordinary coolant to top off a system that is filled with extended-life coolant, the additive packages can interact and reduce the service life to that of regular coolant. The trouble is, you can't always tell if extended-life coolant has been contaminated with regular coolant. Most long-life products are dyed orange while most ordinary coolant is dyed green or yellow. But color shifts can occur naturally as a coolant ages, and it takes a lot of cross-contamination to produce a noticeable color shift with some products.

COOLANT FLUSH
As for an annual coolant flush, it should not be necessary - unless the cooling system contains ordinary antifreeze and the vehicle is driven more than 30,000 miles a year. Changing the coolant every six months would definitely be over-maintaining the vehicle and not necessary.

The only way to know how often a coolant change is needed is to (1) know what kind of antifreeze is in the vehicle's cooling system (which is often difficult if not impossible to tell), and (2) to check the time/mileage since the last coolant change.

One of the best ways to check the condition of the coolant is to use chemical test strips. The test strips change color to reveal both the condition and strength (freezing protection) of the coolant. The test strips react to the level of alkalinity or acidity in the coolant to give a "good" or "bad" reading. If the anti-corrosion additives are depleted, the antifreeze is overdue for a change regardless of time or mileage. Just make sure you use the correct type of test strip for the coolant being tested (regular or extended life). And if you are not sure what is in the cooling system, use a test strip designed for regular GREEN antifreeze.

A visual inspection of the coolant is also a good idea to check for sediment or other signs of contamination. Droplets of oil in the coolant might be the result of a leaky ATF cooler or a leaky head gasket. The presence of sediment or rust would tell you the coolant is not doing its job of protecting the cooling system, and a coolant flush or coolant change are long overdue.

If the system contains Dex-Cool antifreeze and the coolant is full of red muck (which GM says can occur if the cooling system has not been filled properly and there is air in the system), there is a serious problem that will likely require flushing and cleaning the entire cooling system, and possibly replacing the radiator if the muck cannot be removed. The most troublesome applications have been Chevy/GMC S-10 pickups and Blazer/Jimmy models with the cast iron 4.3L V6 engine. These trucks do not have a pressurized coolant reservoir and seem to be prone to air contamination of the coolant.

COOLANT FREEZING PROTECTION
Checking the strength of the coolant is important to make sure the coolant contains a high enough concentration of antifreeze to prevent freezing during cold weather, and boilover during hot weather. You can use a hydrometer or a refractometer for this purpose, but a refractometer usually provides the most accurate results.

If the concentration is low, drain some coolant from the radiator and replace with a compatible antifreeze to increase the freezing protection. A 50/50 mixture of ethylene glycol antifreeze and water will keep the cooling system from freezing up all the way down to -34� F. Increasing the mix to a maximum of 70% antifreeze will keep the coolant liquid down to -84� F!

Never use straight undiluted antifreeze or straight water! Straight antifreeze does not have the heat carrying capacity of water, and may cause the engine to overheat. Straight water provides no freezing protection, no boilover protection and no corrosion protection.

When adding water to a cooling system, use distilled water. Do not use "softened" water because it contains dissolved salt, which can be corrosive, or hard tap water because it contains dissolved minerals that can form lime deposits.

UNIVERSAL ANTIFREEZE?
There are a lot of different types of antifreeze in use today. You'll see orange coolants, green coolants, blue coolants, red coolants, yellow coolants, even pink ones depending on the year, make and model of the vehicle. The proliferation of different coolant types at the OEM level has created a great deal of "chemical confusion" with motorists and technicians about what type of antifreeze should be used to top off or refill late-model cooling systems.

When topping off a cooling system reservoir or replacing the coolant in a newer vehicle, therefore, the safest advice is use an antifreeze that meets the vehicle manufacturer specifications to maintain the OEM warranty requirements. Once the vehicle is out of warranty, however, you can refill the cooling system with virtually any brand or type of coolant so long as it provides adequate corrosion, freezing and boiling protection.

There are essentially three basic types of antifreeze:

One thing the aftermarket has always been good at is consolidation, and today's coolants leave plenty of room for that. In the past couple of years, many antifreeze suppliers have introduced "universal" or "global" one-size-fits-all coolants that are claimed to be compatible with any new vehicle cooling system as well as older vehicles.

The basic idea behind universal coolants is to eliminate all the confusion about colors and chemistry and have one basic product that works in any vehicle regardless of year, make or model. What could be simpler?

Not all antifreeze suppliers buy into this marketing philosophy, so you'll still see the three basic types of coolant being marketed: traditional green for older vehicles and budget-conscious motorists who want the least expensive product on the shelf, an extended-life product that is compatible with Dex-Cool and other OAT-based coolants, and a hybrid OAT for late-model Ford, Chrysler and European vehicles that specify G-05 coolant. But for those who offer a universal "all makes and all models" kind of product, the advantages are obvious: one product that provides full coverage for all applications.

Makers of universal coolants say their products are formulated to be compatible with all cooling systems (import or domestic) and all coolant types (traditional green, OAT and OAT-hybrid with silicate). The new universal coolants use unique OAT-based corrosion packages with proprietary organic acids (such as carboxylate) to provide broad spectrum protection.

When a universal coolant is used to top off a cooling system that already contains an extended-life OAT or hybrid coolant, the service life is unaffected. It remains five years or 150,000 miles. If a universal coolant is added to an older vehicle that has traditional green antifreeze in the cooling system, the service intervals is also the same as before: two to three years or 30,000 to 50,000 miles depending on what was in the system.

COOLANT FLUSH & FILL
When switching to a universal coolant, the cooling system should be flushed to remove all traces of the old coolant when the coolant is changed. Flushing the system removes contaminants and maximizes the service life of the new coolant. Just draining and refilling the radiator is not a complete coolant change because up to a third of the old coolant can remain in the block. If the old coolant is ordinary green coolant, the new universal coolant will be diluted and won't be able to extend protection much beyond that of the original coolant.

The best way to assure a thorough job is to use service equipment that does a complete coolant exchange.

Coolant recycling machines take a different approach by filtering and replenishing the old coolant that is already in the vehicle. Corrosion protection is restored by adding new chemicals to the coolant. Universal additive packages are also available for use with recycling machines, or conventional or OAT-based additive packages for domestic or Asian/European applications.

Bill Created to Make Antifreeze Taste Bitter

Washington, DC - A pack of dogs joined with industry and consumer groups in late-July to urge Congress to pass legislation that would require the antifreeze manufacturers to make their otherwise sweet-tasting product less appealing to animals and children.

As several dogs looked on, representatives of industry and animal rights groups told the Senate Commerce subcommittee on consumer affairs they want legislation requiring coolant manufacturers to put a bittering agent into antifreeze, which is a toxic substance.

Their result - the Antifreeze Bittering Act - has been introduced in Congress, requiring engine coolant that is 10% ethylene glycol to also contain denatonium benzoate, an extremely bitter chemical.

Denatonium benzoate, one of the bitterest substances known, is already used in other household products to discourage children from ingesting them.

Representatives of the Doris Day Animal League told the panel that 1,400 children ingest antifreeze each year, and that as many as 10,000 dogs and cats a year are poisoned by it. Often, it is the poison of choice for disgruntled people seeking to quiet a neighborhood dog.

Subcommittee Chairman George Allen, who invited pet owners to bring their dogs to the hearing, said his panel would act on legislation soon, and that he expected to the full Senate to pass the measure.

A representative from one coolant manufacturer said domestic antifreeze producers also support the legislation. He said the coolant industry, faced with a multitude of state and local laws requiring a bitter tasting product, joined forces last year with the Doris Day Animal League to back a national standard.

Coolant manufacturers said adding denatonium benzoate would add less than 3 cents to the $4 to $6 it costs to make a gallon of coolant.

According to the American International Automobile Dealers Association, the bill would apply only to aftermarket antifreeze sold in retail stores. It would not affect coolants in new vehicles or the drums of replacement fluids used by garages.

The House Subcommittee on Environment and Hazardous Material is reviewing the bill.

Source: Reuters

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