Auto Service World
Feature   May 1, 2004   by John G. Smith

The Rainbow Connection

Despite the wide array of extended life coolant formulas, you may not need to stock every color

Kermit the Frog may insist that it’s not easy being green, but the web-footed sage obviously doesn’t know a thing about coolants. Only a decade ago, ‘flush and fills’ or coolant top-ups involved pouring green fluid into reservoirs. What could be easier than that?

Today’s extended-life coolants may last as long as five years, but the trade-off has come in the form of a dizzying array of formulas and their respective colors, from GM orange, Ford yellow and BMW blue to the recently introduced Toyota purple. Those who service canary-colored Caterpillar diesel engines may even need to reach for a bottle of red coolant from time to time — and the need to keep track of the additional stock can be enough to make you see red all the time.

But despite the wide proliferation of options, shops can avoid stocking every bottle that’s on the market. In fact, some of the latest coolants are being unveiled as one-jug-fits-all solutions. Peak Antifreeze unveiled its Global Extended Life Antifreeze and Coolant in March, offering a product that it says can be used in any automobile without affecting the long-life properties of an existing coolant. Prestone will introduce its own single-jug solution in July, with a Celsius counterpart available for shops by fall. (Peak’s formula is amber and Prestone’s will be a pale green, ensuring that they won’t change the colors of other coolants when used for top-ups.)

“It’s a long-life formula, and we’ve done all the testing to back it up for all the car manufacturers,” says Prestone’s Megan Currie, referring to her company’s pending product launch.


Asian and European manufacturers were the first automakers to experiment with long-life coolants in the 1980s and early ’90s, says Craig Gullett, a brand marketing manager with Peak. The longer life was simply a matter of chemistry.

Traditional green coolants have inhibitor packages that include silicates, phosphates and nitrates to keep ferrous metals from corroding, but these inhibitors tend to deplete more quickly than the carboxylates found in Organic Acid Technology (OAT) formulas, explains Aleksei Gershun, a senior research scientist at Honeywell, which markets Prestone.

By 1995, Volkswagen and General Motors were abandoning their traditional coolants in favor of the longer life that came with an OAT, with GM’s orange formula becoming known as DexCool and offering the “DexCool-approved” stamp to other coolants that were blended with “the right herbs and spices,” Currie says.

Ford and Chrysler later turned to Hybrid Organic Acid Technology (HOAT) coolants that mixed silicates into the OAT, to offer additional protection against corrosion and create products that were still capable of offering five-year drain intervals. The trade-off was a potential mileage that was lower than the 250,000-km life promised by an OAT coolant. (Still, several class action lawsuits in the U.S. claim that DexCool breaks down much earlier than that and leads to corrosion problems; GM counters that the life of the coolant can be affected by operating conditions including environment and terrain.)


Regardless of the technology they choose, automakers tend to balk at any suggestion that coolant types can be mixed. Ford has gone so far as to add “no orange” stickers to its expansion bottles to prevent OAT formulas from being mixed with the HOAT that it prefers. And GM suggested in a recent service bulletin that it would void cooling system warranties if someone decided to use anything other than DexCool.

OAT products are not appropriate for protecting aluminum components from the cavitation-related corrosion that can damage water pumps and aluminum cylinder heads, explains Dr. Dave Turcotte, technical director for Valvoline’s Zerex brand, referring to why the orange mixtures shouldn’t be added to engines that specify the need for HOAT. And the coolant will also “aggressively” attack the solder used in copper and brass radiators.

HOAT might mix into an OAT reservoir with fewer problems, but its use may void the warranties associated with replaced cooling system components, he adds.

While Turcotte agrees that shops shouldn’t need to stock every available color, Valvoline has not opted for a single-bottle solution. Instead, most shops could stock just two types of coolants — an OAT formula for GMs, Asian models and most Europeans makes, and a HOAT formula to cover Ford, Chrysler, Mercedes and John Deere, he says. The latter option can even be used in diesel engines because of the nitrates that can protect against liner pitting. “And you can replace the green coolant with (Ford’s) G05.”

As confusing as the selection of coolants may appear to be, manufacturers even have “contentious discussions” when selecting the colors that will identify them, Turcotte says. It’s often a balancing act between marketing choices and cost. Blue, for example, is cheaper than purple. But most of the bright colors were chosen because many coolant reservoirs are made of blow-molded plastic that yellows with age — lighter colors wouldn’t show through them.

Consumers haven’t taken the same spirited interest. The fact that most retail outlets are still filled with green coolants are a sign of uninformed buyers, Gullett adds, noting that the transition from conventional coolants to their extended life counterparts has been slow. “If that was the case, the market would be shrinking … (and) if people are buying that product, you would see more of it on the shelf.”

The infrequent changes are to blame, he suggests, noting that people are more “attached” to their oil since they have to think about it more often.

Consumers continue to have a number of misconceptions about coolants, agrees Currie, referring to calls to the Prestone hotline that have shown many people don’t even realize they have to mix off-the-shelf products with demineralized water, or buy pre-mixed solutions. “When you’re talking about consumers, a lot of them don’t know what their current mix is,” she says.

Turcotte doesn’t expect the involvement to grow much more. Most consumers won’t think of doing anything more than a top-up, since modern cooling systems can face airlock problems, making a flush and fill more difficult than ever, he says. “I don’t think (most) people are doing it at home in the garage anymore.”


PEAK Global Extended Life Antifreeze & Coolant features a patented, advanced organic acid technology that can be used in all automobiles worldwide, regardless of make, model, year or original antifreeze color. Its patented inhibitors provide maximum cooling system protection against damaging rust and corrosion in all automobiles. PEAK Global Extended Life Antifreeze & Coolant is fully compatible with all quality conventional and new extended life automotive coolants, including GM DEX-COOL and new Ford and Chrysler coolants.

Prestone has revamped their familiar yellow jug formula and has introduced an all makes all models brand. The product will be available in July with a Celsius counterpart available for shops by fall.

Zerex G-05 is a long-life, universal, ethylene glycol-based hybrid formulation suitable for passenger cars, light trucks and heavy-duty vehicles. Its low pH, hard water stabilized, phosphate-free European technology protects all cooling system metals, including aluminum, from corrosion. The fully formulated coolant is also designed to protect heavy-duty diesel engines. The DaimlerChrysler and Ford alternative products to the Zerex G-05 are Mopar MS-9769 and Motorcraft Gold respectively. The DaimlerChrysler and Ford warranties will be void if any other formulation is used, according to the manufacturers.

Print this page


Have your say:

Your email address will not be published. Required fields are marked *