How to combat rust - public enemy No. 1 to your car

No matter where you live - the Northeast, Florida, the Texas panhandle, or mountainous Colorado - rust is likely to be working on your car. Vehicles in the snowbelt states, where salted roadways in winter accelerate corrosion, are usually thought to be the most vulnerable to rust. Yet road salt is not the only culprit involved in the corrosion process. Humidity, condensation, salt air, and frequent temperature changes can also promote rusting. The salt-air environment in Florida can be just as damaging to car bodies as salted roadways.

In recent years both foreign and domestic automakers have come under heavy consumer criticism for not making their products more rust resistant. Owners of Dodge Aspens and Plymouth Volares, Hondas, and several Ford models produced in the late 1970s, among others, can attest to the early destruction of their cars because of perforation rust (from the inside out).

As a result, some car companies now rustproof their vehicles either during the assembly process or later at new car dealerships through company-sponsored (rustproofing) programs.

Ford Motor Company is one manufacturer that now offers dealer-installed rustproofing as an option to new car buyers and backs it up with a tough warranty. Under Ford's Superseal program, Ford dealers rustproof new vehicles according to company specifications. In return, the company warrants the vehicle against perforation rust for the life of the vehicle.

''If you're going to spend money on rustproofing to protect your car,'' says Warren LeBaron of Ford, ''you should at least have it guaranteed.''

While the auto industry has made progress in reducing automotive corrosion in recent years by using more aluminum, galvanized metals, and zinc-coated steels, the environment that breeds rust has gotten worse.

The amount of road salt spread on US highways each year to fight ice buildup is estimated at close to 12 million tons. The increased use of calcium chloride, which is more corrosive than sodium chloride (ordinary table salt) because of its increased effectiveness at lower temperatures, adds to the already bad corrosion problem.

Alternatives to road salt are now under development. Pennsylvania State University researchers, for example, have developed a way to give cars better traction when it's too cold for road salt to dissolve ice.

The process calls for the application of oven-heated sand to an ice-covered road. The sand first melts the ice, then freezes into it, giving vehicles better control during skidding, according to Gordon Hayhoe, an assistant professor of mechanical engineering at the school.

Despite success in the lab, however, the process is not yet ready for widespread use. An economical way to heat the sand and a practical way to dispense it must be developed first.

Even acid rain, which is destroying many ponds and lakes in the Northeastern part of the United States and in Canada, adds to the corrosive environment to which a car is subjected. Road salt reacts with the acid rain, called a synergistic reaction, making them far more corrosive together than either would be alone.

What steps besides rustproofing can a car owner take to forestall an early appointment with the junkyard?

Possibly the easiest and most effective thing you can do to ensure the life of your car's body is to wash it frequently. Washing with a mild detergent and a soft sponge cleans off the mud, salt, and dirt that will eventually wear off the wax. While washing the top and sides of the car, don't forget to flush out the vehicle's undercarriage, where dirt and salt can accumulate. A word of caution: Avoid washing your car during subfreezing weather, because the water in the door locks and window tracks will freeze, possibly locking you out. Driving the car after washing it will help to dry out any moisture that still hides in the cracks and crevices of the body.

Finally, try to wax the car's painted surfaces at least twice a year. Wax will protect the paint, but it will eventually wear off. Remember, if water beads up on the paint, the wax is working. If it does not, you are probably overdue for a complete wax job.