Choosing The Correct Antifreeze
First of all the word Antifreeze is very misleading in today's cars. Every
article I have read, Antifreeze is mentioned as a rust inhibitor and lubricant,
no one worries about the temperature issues.
Have you ever seen the inside of
an aluminum water pump that was not adequately protected by the corrosion
inhibitors in the coolant? Or a radiator or heater core that failed from the
inside out because of internal corrosion? These kinds of parts failures are all
too common. Yet they can be easily prevented by using the “right” coolant and
changing the coolant before trouble starts to heat up.
All types of antifreeze contain corrosion-inhibiting chemicals to protect bare
metal surfaces from electrolytic attack. Though automakers disagree on which
chemical additives work best in their vehicles, essentially any kind of
antifreeze will work in any vehicle. But how well will it protect the cooling
Always refer to the repair manual before topping off your vehicle's
What makes choosing the right coolant so confusing today is that the
automakers themselves can’t agree on what type of coolant chemistry is best for
their vehicles. Some vehicle manufacturers prefer one type of corrosion
inhibitors in their coolants, while other vehicle manufacturers may insist on a
The fact is, all types of antifreeze contain additives to protect the cooling
system against corrosion. So you wouldn’t think it would make any difference
which one you actually decided to use. But some corrosion inhibitors are not
compatible with others, and if the chemistries differ too much, it can reduce
the coolant’s ability to prevent corrosion as the coolant ages.
Adding a conventional green antifreeze to a cooling system that contains an
orange or yellow long-life coolant will reduce the life of the coolant to that
of ordinary antifreeze (which for most vehicles is typically two to three years
or 30,000 miles). Most long-life coolants, by comparison, are formulated to go
five years or 150,000 miles.
To distinguish one type of coolant from another, vehicle manufacturers add
colored dye to their coolants. Unfortunately, the colors they use are not
necessarily standardized and do not always conform to the same chemical
specifications. Because of this, two different coolants may use the same color
dye, or two similar coolants may use different colored dyes. Most standard
formula antifreeze is dyed green, but there are also some standard formula
coolants that are yellow. Long-life coolants are typically orange or yellow, but
some may also be red, pink, blue, purple or even green. Go figure. Consequently,
the idea of matching colors when choosing a coolant doesn’t always guarantee
The Standard Green
Standard green formula antifreeze is the type that most North American
vehicles used until the introduction of extended-life coolants back in the
mid-1990s. This type of coolant contains fast-acting silicate and phosphate
corrosion inhibitors that protect cast iron engines, bi-metal (cast
iron/aluminum) engines, and copper/brass and aluminum radiators. The
corrosion-fighting chemicals are fast-acting, but wear out after two to three
years or 36,000 miles of average use, so green coolant needs to be changed
periodically to minimize the risk of corrosion damage.
While this type of antifreeze is primarily for older vehicles (pre-1996), it can
also be used in virtually any vehicle application (domestic, Asian or European)
regardless of year — provided all of the old coolant is completely flushed and
replaced with new.
Extended Life OAT Formula
Antifreeze that is dyed orange, typically contains “Organic Acid
Technology” (OAT) corrosion inhibitors such as sebacate, 2-ethylhexanoic acid
(2-EHA) and other organic acids, but no silicates or phosphates. The most
familiar OAT-based product is Dex-Cool, which General Motors has used since
1996. Orange formula coolant is also used in the Mercury Cougar, and 2003 and up
Saabs. Similar formulas include a pink-colored coolant in late-model Audi and
Volkswagen vehicles and a dark green coolant in Hondas.
The corrosion inhibitors in OAT coolants are slower acting than standard green
formula coolant, but last much longer. The service life for this type of coolant
is five years or 150,000 miles — which seems like a long time, but it is not a
lifetime coolant. Eventually the corrosion inhibitors wear out and the coolant
needs to be changed.
Extended Life Hybrid Coolants
Silicated Hybrid Organic Acid Technology (HOAT) antifreezes, which are
sometimes referred to as “G-05” formula coolants, contain organic acids in
combination with one or more inorganic inhibitors. The most common inhibitor is
silicate. The addition of silicates increases corrosion protection for aluminum
engines, radiators and heater cores, and helps protect the water pump against
erosion wear. Silicated hybrid OAT coolants are specified for 2001 and up
DaimlerChrysler vehicles, 2002 and up Ford trucks and SUVs, 2003 and up Ford
passenger cars, and 1985 and up Mercedes, BMWs, Volvos and Mini Coopers.
“Phosphated HOAT” coolants are used in Asian vehicles (Toyota, Honda, Nissan,
Kia and Hyundai) because Asian vehicle manufacturers prefer phosphated organic
acid coolants and do not like silicated organic acid coolants. European vehicle
manufacturers, on the other hand, generally specify silicated HOAT coolants and
do not like phosphated organic acid coolants. That’s why some antifreeze
suppliers offer different HOAT formulas for these applications.
Universal formula antifreezes are marketed as being suitable for all
passenger cars and light trucks, regardless of year, make or model, or the type
of coolant that’s already in the cooling system. Some of these claims have been
challenged in court on the basis that no single additive package can match the
conflicting requirements of different OEM coolants. Even so, the makers of
universal coolant say their products can be used in any vehicle, whether it
matches the original coolant chemistry or not.
The universal coolants use OAT-based corrosion inhibitors with proprietary
organic acids to provide broad spectrum protection. The coolant may be dyed
yellow or amber (yellow-orange).
The service life of most universal formula products is typically five years or
150,000 miles — with one exception. When used to top off a cooling system in an
older vehicle that contains standard green formula coolant, the service life of
the product is reduced to that of the original coolant, which is two to three
years or 30,000 miles.
The main advantages of a universal coolant is that it simplifies the selection
process to a single product, and it eliminates the need to carry three different
types of coolant (green, orange and yellow hybrid) to cover the market.
Those who are opposed to universal coolants say one product cannot match the
conflicting coolant requirements of all the different vehicle manufacturers, and
that it is safer to offer three different types of coolants that meet these
specifications. Consequently, many parts stores carry not only the three basic
types of coolant just described (often in several different brands), but also a
universal coolant for customers who prefer that type of product. When choosing a
coolant, therefore, refer to the vehicle owner’s manual for the type recommended
(or the label on the coolant reservoir under the hood) to find a coolant that
meets the OEM requirements. Or, you may want to choose an acceptable universal