Rick's Free Auto Repair Advice

Switch to green coolant?

Should you switch to green coolant?

Is it ok to switch to green coolant instead of factory coolant?

Since not all auto parts stores stock all factory coolants, many people ask if they can switch to green coolant. You can, but that decision will cost you over the long term. The damage won’t show up right away. In fact, a year or two down the road when your water pump starts leaking or your heater core springs a leak, you probably won’ think it was caused by using the wrong coolant. But the truth is, using the right coolant is CRITICAL to maintaining the proper anti-corrosive additives in your coolant system. Plus, the right coolants will be compatible with seals, gaskets and rubber parts. Here’s a rundown on some of the antifreeze types, along with some manufacturer warnings about which ones you should use.

It’s a difference of about $10/gallon. Why would anyone risk early radiator, water pump or heater core failure to save $20 (two gallons x $10)?

What is IAT Green coolant?

The old green coolant is made with approximately 95% polyethylene glycol and an inorganic acid switch to green coolanttechnology (IAT) additive package. The additives contain:

• Sodium or potassium salts of inorganic anions like phosphate, borate, silicate, nitrite and nitrate.

• Azole compounds like tolyltriazole, benzotriazole, or mercaptobenzothiazole as a copper corrosion inhibitor.

Silicates or phosphates act quickly to prevent corrosion on bare iron and aluminum surfaces. They deposit on the walls of the metals to form a “passivating” ANODIC coating. As soon as the ANODIC layer is higher than the cathodic current, the system is considered “passivated.” In other words, it’s the coating that eliminates electroylsis caused when different metals are used in a cooling system. There are two downsides to traditional green coolants though.

• First, the additives precipitate out of the solution, so they have a shorter life of less than 30,000 miles.

• Borate is also an anodic corrosion inhibitors that works best with cast iron engine parts, but is corrosive to aluminum and aluminum alloys

• Silicates and phosphates are somewhat abrasive and can cause accelerated damage to water pump seals.

• Green coolant reacts poorly with hard water, forming scale in the cooling system that can plug the radiator and heater core.

• Nitrates have a short life and don’t work well to protect aluminum or aluminum alloys.

As the passivating film deteriorates, the metals develop pitting and the corrosion accelerates.

Silicates and phosphates are designed to protect copper, brass, cast iron and aluminum. It is NOT recommended for use on newer cars that were filled with OAT or HOAT coolants.

What is OAT ORANGE coolant?

Organic Acid Technology can be formulated to act as

green coolant

OAT DexCool

either a CATHODIC or ANODIC inhibitor, or a combination of the two. Like green coolant, it’s also made from a ~95% polyethrlene glycol base plus an additive package.

When formulated to inhibit the CATHODIC reaction, the additives contain metal ions like magnesium, zinc, and nickel that precipitate onto cathodic metals within the engine and cooling system to form an adherent film.

OAT coolants contain: 2-ethylhexanoic acid, sebacic acid, azelaic amines, urea, Mercaptobenzothiazole (MBT), benzotriazole e toliotriazol, aldehydes, heterocyclic nitrogen compounds, sulfur-containing compounds and acetylenic compounds and also ascorbic acid, succinic acid, tryptamine, caffeine and extracts of natural substances. OAT coolants also contain an azole additive as a copper corrosion inhibitor.

OAT coolants form a hydrophobic (tending to repel or fail to mix with water) film on metal components. While the protective layer lasts much longer than IAT formulas, they also take much longer to form that initial film.

OAT Coolant advantages

Organic acid inhibitors protect aluminum and cast iron components. They are non-abrasive, so they don’t damage water pump seals. However, the exact formulation MUST be compatible with the plastic and rubber components used in a particular engine/cooling system combination. Using OAT in older cast iron engines or newer engines with different gasket and seal types can cause cooling system leaks and failures.

What is HOAT blue, red, pink, yellow coolant?

Hybrid organic acid technology is a combination of IAT and OAT that

switch to green coolant


includes an organic ANION as the primary corrosion inhibitor along with an inorganic corrosion inhibitor. For example, HOAT often includes an organic acid and low silicate inhibitor. The inorganic portion provides rapid passivation until the organic acid can take over.

green coolant

G-40 Pink Coolant

nitrites are added to the mix. Aftermarket coolant manufacturers refer to this blend as a Universal Antifreeze, when in fact, there is no such thing. Each car makers recommends a certain type of coolant and owners should follow the car makers recommendations, not those of the aftermarket coolant manufacturers. Think about all the different metals in a cooling system. You’ve got an aluminum radiator, aluminum alloy block and cylinder heads, steel coolant tubing, a copper heater core, and magnesium water pump castings. That’s a lot of different metals that

switch to green coolant

Red coolant

create electrolysis that can eat away at your cooling system. Why jeopardize it by using the wrong coolant?

Orange HOAT used in Chrysler vehicles contains 10% recycled coolant. HOAT used in Ford vehicles is virgin and is YELLOW in color. Both have a listed life of 5 years or 150,000 miles.

Chrysler is also using a new purple coolant and it’s NOT compatible with other coolants. To read more about the purple coolant, click on this link.

HOAT coolants come in various chemistries

G-05 is used by most European manufacturers

G-11 or G-12 is used by VW and Audi

Can you mix different types of coolants?

Absolutely not. Car makers formulate gaskets, seals, and metal parts based on a certain coolant formulation. If you install the wrong coolant or mix coolants, you introduce non-tested chemicals that can interact to form acids and sludge. Car makers are now seeing evidence that the wrong coolant and mixed coolants can destroy seals, gaskets, and metal components in as little as six weeks. In fact, Gates, a major manufacturer of water pumps has now come out with a return policy that will reject warranty claims on any pump where there’s evidence of incorrect coolant and deterioration of the metal. Yes, it’s that serious of a problem.

What can happen if you switch to green coolant?

If your factory fill was phosphated HOAT pink and you switch to Green coolant:

The silicate, borate, nitrite or amine containing additives can harm the metals in your engine.

If your factory fill was phosphated HOAT blue and you switch to Green coolant:

The silicate, borate, nitrite or amine containing additives can harm the metals in your engine.

If your factory fill was phosphated HOAT red and you switch to Green coolant:

The silicate, borate, nitrite or amine containing additives can harm the metals in your engine.

What do the car makers have to say about switching to green coolants?

Read what the car makers said— from Aftermarket Business Magazine, July 2006

“John Conville, a coolant expert at Ford Motor Co., emphasizes that Ford does not recommend the use of any specific aftermarket coolants in their vehicles (unless approved). “…the only aftermarket coolants that Ford recommends are the appropriate Motorcraft brand engine coolants.” With the use of non-approved coolants, Ford is concerned about “corrosion of metals and incompatibility with some of the polymeric materials we use in our vehicles.”

“Due to the complexity of cooling systems, no one coolant has been proven to work in all vehicles,” and “use of non-approved ‘universal’ engine coolants may lead to eventual engine damage or failure. Problems caused by the use of non-approved ‘universal’ coolants may not arise immediately but may occur over longer periods of time due to additive compatibility issues.” Conville says they do not have specific test results on such coolants because “there are many different coolants in the North American aftermarket and Ford does not have the resources to test them all.”

Chrysler states: “Mixing of coolants other than those specified (i.e. non-HOAT) may result in engine damage that may not be covered under the new vehicle warranty, and decreased corrosion protection. If a non-HOAT coolant is introduced to the cooling system in an emergency, it should be replaced with the specified coolant as soon as possible.” An antifreeze antidote, Aftermarket Business, July 2006

Consumers need to be careful of what they buy because it’s a chemical manufacturer’s job to sell coolant and they “enhance their ability to sell coolant by making claims that a coolant is compatible with all the carmakers. We know from the formula that some of them don’t work.”   GM spokesperson Lockwood

Ed Eaton, chief engineer at Amalgatech, a professional automotive fluids and heat exchange independent testing lab, explains that Ford and DaimlerChrysler both use Valvoline G-05®, a European-style hybrid formula. Most Japanese automakers use a hybrid formula too, but it is vastly different. And General Motors uses DEX-COOL®, an organic acid technology (OAT) formulation.

Toyota, which has long life and super long life non-silicated products, too, does not advocate the use of non-genuine antifreeze/coolants. Toyota Motor Sales’ Bill Kwong in product communications explains that other formulas tested didn’t provide the same performance. “Evaluations of competitive formulations have been made in simulation and field tests, showing (Toyota’s) product superior in water pump seal protection, leakage and deposit formation.” It’s uncertain whether he’s referring to competitive OEM or aftermarket formulas.

What the coolant manufacturers have to say about switching

The Valvoline Co., a division of Ashland Inc. and the maker of Zerex® antifreeze products, recommends following the OEM’s formulation suggestions. Valvoline’s David Turcotte, technical director of the company’s Technology and Product Development division, believes that in some instances of damage, “cause and effect isn’t always obvious.” Other than the apparent compromises in performance, much of the physical damage caused by improper coolant use is not noticed until the cooling system is dismantled, said Turcotte at a recent product presentation.

Consumers need to be careful of what they buy because it’s a chemical manufacturer’s job to sell coolant and they “enhance their ability to sell coolant by making claims that a coolant is compatible with all the carmakers. We know from the formula that some of them don’t work.”   GM spokesperson Lockwood

Is it OK to drive a vehicle that’s a little low on coolant?

NO! Coolant vapors take up the place of liquid coolant and that vapor is far more corrosive than either the raw coolant or water. Run your vehicle low on coolant you can expect some very expensive repairs.

Ever if your car doesn’t overheat if you drive it while low on coolant, you can do substantial damage to the engine when you shut it down. At shut down, the heat rises towards the top of the engine, which is where air pockets develop when you’re low on coolant. That air becomes super heated and causes boiling. The differences in temperature can cause cylinder heads to warp. That’ll cost you several thousand dollars.

© 2009 Rick Muscoplat

Posted on by Rick Muscoplat

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