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Copyright AA1Car Adapted from an article written by Larry Carley for Underhood Service magazine
For nearly a decade, vehicle manufacturers have been introducing and using a variety of extended-life coolants. The only thing these coolants have in common is that they all seem to differ in formulation and color. There are orange coolants, green coolants, blue coolants, red coolants, yellow coolants, even pink ones. The proliferation of different coolant types 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.
We are not going to summarize the whole laundry list of OEM coolants and colors here except to say that each vehicle manufacturer has their own unique coolant specifications based on corrosion protection requirements, service life and chemical compatibility. These requirements are usually spelled out in the vehicle owners manual, and/or a decal or label on the coolant reservoir. It is important to always use the coolant chemistry recommended in the vehicle owners manual. For example, Ford and Chrysler specify hybrid OAT-only coolants.
You cannot go by the color of the dye in the coolant because two coolants with similar colors may have different chemistry, and two coolants with different colors may have similar chemistry. What is more, colors can change if somebody tops off the system with a different coolant.
The more we get into the specifics of each type of coolant, the more confusing the whole discussion becomes - so we are only going to tell you what is really worth knowing with respect to the different types of antifreeze.
There are essentially three basic types of antifreeze:
Traditional North American GREEN antifreeze, the original universal formula that everybody used until the introduction of today is extended-life coolants. The fast-acting silicate and phosphate corrosion inhibitors provide quick protection for bare iron and aluminum surfaces, and have a proven track record of providing trouble-free service in virtually any vehicle application (domestic, Asian or European), assuming the chemistry is correct. For example, OAT coolants should not be used in a vehicle that specifies the use of a hybrid OAT coolant. Again, always defer to the owners manual. But the short-lived nature of the corrosion inhibitors means this type of coolant should be changed every two to three years or 30,000 miles (though some products now claim a service interval of up to 50,000 miles with improved chemistry).
OAT-based extended-life coolants. OAT stands for Organic Acid Technology, and includes such ingredients as sebacate, 2-ethylhexanoic acid (2-EHA) and other organic acids, but no silicates or phosphates (except in the case of Toyota's pink extended-life coolant, which adds a dose of phosphate to its extended-life OAT-based antifreeze). OAT-based coolants are usually (but not always) dyed a different color to distinguish them from traditional North American green antifreeze. GM OAT-based Dex-Cool is orange. Volkswagen/Audi uses a similar product that is dyed pink. But Honda has an extended-life OAT coolant that is dyed dark green and does not contain 2-EHA.
The corrosion inhibitors in OAT coolants are slower acting but much longer-lived than those in traditional North American green coolants. Consequently, OAT coolants typically have a recommended service life of five years or 150,000 miles (which ever comes first - which means you should change the coolant after five years and NOT wait until the odometer says 100,000 to 150,000 miles).
OAT corrosion inhibitors provide excellent long-term protection for aluminum and cast iron, but may not be the best choice for older cooling systems that have copper/brass radiators and heater cores. It depends on the formula. A conventional green formula antifreeze is usually best for older vehicles with copper/brass radiators.
Hybrid OAT coolants, also known as HOAT antifreeze or G-05 antifreeze. This formulation also uses organic acids, but not 2-EHA (different organic acids are used). Hybrid OAT coolants add a small dose of silicates to provide quick-acting protection for aluminum surfaces. Hybrid OAT coolants are currently used by many European and Asian vehicle manufacturers as well as Ford and Chrysler. Some aftermarket antifreeze suppliers have introduced HOAT coolants specially formulated to meet the unique requirements for Asian cars and for European cars. The colors of these coolants may or may not match the color of the OEM coolants. It doesn't matter as long as the chemistry is compatible.
As HOAT antifreeze ages, however, some of the silicates may drop out of solution. These particles can have an abrasive effect as they circulate in the cooling system, accelerating wear on water pump seals and plastic impellers, plastic radiator end tanks, or inside metal heater cores with sharply curved tubes. To avoid these kinds of problems, most HOAT-based antifreezes use stabilizers to keep the silicates in solution, and they contain only a small amount of silicates. HOAT-based antifreezes that claim to be "low silicate" formulas should meet the ASTM D6210 standard (which is a requirement for most late model diesel engines).
Like-OAT-based antifreezes, HOAT-based antifreezes also have a claimed service life of 5 years or 100,000 to 150,000 miles -- which ever comes first.
WHICH TYPE OF ANTIFREEZE SHOULD YOU USE?
Which type of coolant should you use to top off or refill your cooling system? If you vehicle is still under warranty (and that includes extended powertrain warranties), you should use the same type of antifreeze that is specified by the vehicle manufacturer.
For General Motors vehicles, that would be Dex-Cool or an antifreeze that meets GM6277M, ASTM D3306, SAE J1034, J814 and J1941,
TMC of ATA RP-302B, or Federal Specification A-A-870A.
If your drive a Ford, it would be an antifreeze that meets Ford WSS-M97B51-A1 specs.
If you drive a 2001 or newer Chrysler, it would be Chrysler antifreeze that meets Chrysler MS9769 specs for a GO-5 or HOAT (Hybrid Organic Acid Technology) type of coolant.
Check in your owners manual to see what type of coolant is specified for your vehicle.
Once your vehicle is out of warranty, you can use the same type of antifreeze that came in the cooling system from the factory, or you can switch to a "Universal" or Global" coolant that is compatible with all makes and all models.
The term "Universal Coolant" seems like a contradiction because of all the different antifreeze requirements we just described. Even so, universal coolants are formulated to mix with virtually any coolant. The makers of these product say their antifreeze can be safely used in any year, make or model of vehicle.
Antifreeze Application Charts:
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?
. . Brands that promote Universal Coolants . .
Not all antifreeze suppliers buy into this marketing philosophy, so you will 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 or two SKUs to provide full coverage (full-strength antifreeze or 50/50 mix), less shelf space needed to stock the product, and most importantly, no confusion over which product to use in which application. And for the vehicle owner, it means you only have to buy one jug of antifreeze that can be used in any car or truck you own.
Makers of universal coolants say their products are formulated to be compatible with all cooling systems (foreign 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 (which ever comes first). If a universal coolant is added to an older vehicle that has traditional green antifreeze in the cooling system, the service interval is also the same as before: two to three years or 30,000 to 50,000 miles.
If a cooling system is being refilled with a universal coolant, the cooling system should be flushed to remove all traces of the old coolant. This is necessary to remove contaminants and to maximize the service life of the new coolant. If only the radiator is drained, up to a third of the old coolant can remain in the block.
If the old coolant is traditional green coolant, the new universal coolant will be diluted and won't be able to extend protection much beyond that of the original coolant.
One very important point to keep in mind here is that universal coolants and extended-life coolants are NOT lifetime coolants. The corrosion inhibitors in all types of coolant eventually wear out and must be replenished by changing the coolant. After five years of service, most coolants still need to be changed. Leave the old coolant in too long and the cooling system will experience corrosion problems.
Update: November 2012
Chrysler Switches to New Coolant for Model Year 2013
Though Chrysler has used G-05 HOAT low-silicate formula coolant for over a decade, it is changing formulas for model year 2013. The new coolant will be a straight OAT type coolant, dyed orange, but it is NOT Dex-Cool (which GM uses). The new Chrysler OAT coolant will NOT contain 2-EHA (2-ethylhexanoate) which can soften gaskets and seals that contain silicone. The service life of the new coolant will be 10 years or 150,000 miles, which ever comes first, and it will be the factory fill coolant for all cars and light trucks.
More Coolant Related Articles:
Coolant Checks & Changes More Complicated These Days
Finding & Fixing Coolant Leaks
Servicing Your Cooling System
Your Temperature Warning Lamp Is On. What Should You Do?
Overheating: Causes & Cures
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