Changing antifreeze coolant helps check car corrosion

WARNING! Do not neglect the antifreeze coolant in your car's radiator. It should be changed at least every two years! Corrosion can extend far beyond the body metal in a car, says Dr. Robert Baboian, head of the electrochemical and corrosion laboratory at Texas Instruments (TI). Consider the radiator coolant and exhaust system as well.

With the automobile companies switching to newer engine designs and aluminum heads, radiators, and the like, it doesn't take too much breaking down of the corrosion inhibitors in the antifreeze coolant before the aluminum begins to corrode.

``When the aluminum corrodes,'' Dr. Baboian notes, ``then you begin to have serious problems, such as the plugging of the radiator with the products of corrosion.'' And it doesn't take much plugging to overheat the engine and result in serious, and costly, problems to the motorist.

To combat the problem, TI has developed a coolant-condition sensor that will be used in some 1987-model cars, such as the Chevrolet Camaro. The sensor tells when the coolant becomes corrosive and it's time to put in fresh antifreeze.

Automakers, too, have developed cooling systems specifically for aluminum, such as antifreezes that have inhibitors and incorporate corrosion resistance for aluminum, ``but even they can break down with time,'' notes Boboian. When a motorist replaces the car's coolant, for the most part he isn't changing it for its antifreeze capability, but rather for the additives that inhibit corrosion.

The exhaust system requires replacement, for the most part, because of corrosion, both inside and out. First, there are the high cyclic temperatures and acids inside the system and the severe road salt and acid environment on the outside. The catalytic-converter system and front pipe from the engine rarely rust, because they are fabricated of higher-alloy materials.

Lifetime mufflers are made from either high-grade stainless steel or aluminized steel.

TI is also working on a sensor that would tell a motorist when the engine oil of his car is becoming corrosive.

``Changing the engine oil regularly is extremely important,'' he asserts, ``and most people don't do it. In all engines the products of combustion get into the oil and corrode it. An oil change is the cheapest car insurance you can buy.''

Charles E. Dole is the Monitor's automotive editor.

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