Danny

Looking for imput and experience from everyone regarding this thread. Protecting the cooling system of our cars is probably on the top of the maintenance list. Please contribute so that we can share the best advice as possible with everyone.


Coolant Information

Recently, several people have questioned whether the coolant (anti-freeze) sold by Honda and Acura dealers is different from the popular mass-market brands.

Honda has sent the information attached below to its dealers to provide technical information and justification for differences in their formula.

Genuine Honda Coolant is the Only Way to Go -------------------------------------------

Increasingly severe operating conditions and the advent of lower maintenance requirements have resulted in significant changes in the variety and the concentration of additives used in engine coolant. Also, the continual improvements in engine and vehicle design have challenged coolant suppliers to design products that perform well in a more demanding environment.

To meet these needs, Honda engineers have developed a superior, high-quality coolant that has several advantages over the competition.

Some antifreeze, although labeled as safe for aluminum parts, may not be compatible with Acura cooling system components. Extensive research and testing by both Honda R&D and CCI, the manufacturer of the Honda coolant, have proven that the abrasive silicates and/or borates found in most domestic coolants can cause these problems:

- Silicates bond to the surface of the water pump seal and act as an abrasive, causing considerable seal erosion and coolant leakage. In actual tests, the silicated coolant caused early leakage. This leakage increased dramatically until a substantial portion of the coolant had been lost. In contrast, the Honda coolant had almost no leakage through the duration of the test.

Chart here, entitled "Coolant Leakage from Water Pump Seal", showing Leaked Coolant Volume in ml as follows for each test duration in Hours:

24 hrs: Honda Coolant 0, Typical Silicated Coolant 21 48 hrs: Honda Coolant 1, Typical Silicated Coolant 36 72 hrs: Honda Coolant 2, Typical Silicated Coolant 47 96 hrs: Honda Coolant 2, Typical Silicated Coolant 55 120 hrs: Honda Coolant 2.5, Typical Silicated Coolant 56 144 hrs: Honda Coolant 3.5, Typical Silicated Coolant 57 168 hrs: Honda Coolant 4, Typical Silicated Coolant 58.8 192 hrs: Honda Coolant 6, Typical Silicated Coolant 63 200 hrs: Honda Coolant 6, Typical Silicated Coolant 64

- Silicates tend to gel and settle in the coolest parts of the cooling system, causing radiator plugging and overheating.

- Borates cause pitting corrosion on the cylinder head.

- Silicate inhibitors are difficult to stabilize and, therefore, limit coolant shelf life.

Most commercially available coolants were originally designed for cast iron engines. Silicate, an inexpensive additive, was added to coolants to prevent aluminum corrosion, but the long-term durability of the combination was not tested.

In contrast, Honda coolant was designed specifically for aluminum engines. It contains an organic corrosion inhibitor instead of silicate. This superior formula gives these advantages:

- No silicate abrasion of water pump seals. For example, these graphs show the surface roughness of two aluminum water pump seal rings. Seal A, exposed to silicated coolant, shows considerable damage. Seal B, exposed to Honda coolant, displays only minute wear.

(graphs here, showing roughness across the surface, with A a very wiggly line, and B a very smooth line)

- No plugging or overheating caused by silicate gelling.

- Excellent corrosion protection for aluminum components.

- Long-term corrosion protection for other cooling system materials (steel, cast iron, copper, solder, gaskets, seals, and O-rings).

You can find less expensive coolants on the market, but now you can see why genuine Honda coolant is the only coolant approved for Honda and Acura vehicles (it MUST be used for warranty repairs). Honda's non-silicate formula delivers added protection not offered by 95 percent of other brands. Since our customers expect lower maintenance, you're doing them an injustice if you use any other coolant.

I believe this service should be done every 30,000 miles or 24 months to keep your cooling system clean and considering the overheating and head gasket issues many of us have had.


Note:
Several antifreeze suppliers have just recently introduced "long life" antifreeze formulations that claim to provide protection for four years or 50,000 miles.
General Motors just introduced a new five year, 100,000 mile antifreeze in its 1996 cars and light trucks. The new coolant is called "Dex-Cool" and is dyed orange to distinguish it from ordinary antifreeze (which is green).

CAUTION: These new long life coolants provide extended life only when used in a clean system mixed with water. If mixed with ordinary antifreeze and/or old coolant in a system, the corrosion protection is reduced to that of normal antifreeze (2 to 3 years and 30,000 miles).

CORROSION INHIBITORS
The life of the antifreeze depends on it's ability to inhibit corrosion. Silicates, phosphates and/or borates are used as corrosion inhibitors to keep the solution alkaline. As long as the antifreeze remains so, corrosion is held in check and there's no need to change the coolant. But as the corrosion inhibiting chemicals are used up over time, electrolytic corrosion starts to eat away at the metal inside the engine and radiator. Aluminum is especially vulnerable to corrosion and can turn to Swiss cheese rather quickly when conditions are right. Solder bloom can also form in copper\brass radiators causing leaks and restrictions. So changing the coolant periodically as preventative maintenance is a good way to prevent costly repairs.

The basic idea is to change the coolant before the corrosion inhibitors reach dangerously low levels. Following the OEM change recommendations is usually good enough to keep corrosion in check, but it may not always be the case. That's why more frequent changes may be recommended to minimize the risk of corrosion in bimetal engines and aluminum radiators.

CHECKING THE ANTIFREEZE
One way to find out if it's time to change the antifreeze is to test it. Several suppliers make special antifreeze test strips that react to the pH (alkalinity) of the coolant and change color. If the test strip indicates a marginal or bad condition, the coolant should be changed.

CHANGING THE COOLANT
Reverse flushing is the best way to change the coolant because draining alone can leave as much as 30 to 50% of the old coolant in the engine block. Reverse flushing also helps dislodge deposits and scale which can interfere with good heat transfer.

The concentration of antifreeze in the coolant also needs to be checked prior to the onset of cold weather. A 50/50 mixture of antifreeze and water is recommended and will protect against freezing down to -34 degrees F and boilover protection to 263 degrees F.