An estimated 18 million automatic transmissions fail each year, costing the motoring public billions of dollars in repairs.

Failures have grown more commonplace during the last several decades as transmissions have gotten more complex. The result: Automatics have become problematic items that can drop $2,000 repair bills out of the clear-blue sky.

It’s a painful irony, given that many other automotive innovations--things like radial tires, fuel-injection systems and stainless-steel exhausts--have improved in reliability through the years.

Why are these transmissions so bad? At the same time that automatic transmissions were being downsized to fit smaller engine compartments, designers reduced the airflow around transmissions and increased the workload they perform.


The majority of transmissions fail because of overheating, which in turn causes a breakdown of transmission fluid and a resulting loss of lubrication.

Unlike motor oil, transmission oil performs a variety of tasks. It lubricates moving parts, acts as a hydraulic fluid to operate valves, transfers power through the fluid clutch and is the sole coolant inside the transmission housing.

Although this won’t help older transmissions, car makers are developing a range of new transmission fluids, aiming to provide fluids that never need to be changed, said Norm Hudecki, an oil expert and former research chief at Valvoline Oil. For example, Ford Motor Co.'s new Mercon 5 is billed as a lifetime fluid. Dextron 3 will be guaranteed by General Motors Corp. to run 100,000 miles between changes.

The new fluids are intended to alleviate the problem of motorists not paying attention to fluid changes and suffering transmission failures.


“Most people do not change their automatic transmission fluid when they are supposed to,” Hudecki said.

*

Although car owners are routinely implored to change their engine oil every 3,000 miles, few individuals are aware of the potential damage to their transmissions from running oxidized and contaminated transmission fluid.

Front-wheel-drive systems on cars, introduced in the 1980s, added dramatically to the complexity of transmissions. The systems required that the differential and the transmission be combined into a single smaller unit, called the transaxle.


The transaxle had to be crammed into a much smaller space under the hoods of newer cars. At the same time, cars were given greater aerodynamic efficiency, meaning that grilles were made smaller, reducing the amount of air circulating under the car. All of this resulted in higher temperatures for the transmission.

But if the newer fluids cannot be used in older transmissions, then what can be done? If you have a model with a known history of transmission failure, you should opt for annual transmission fluid and filter changes.

Another option to consider is the use of an additive, such as Lubeguard, which is widely used by repair and remanufacturing shops to improve the operation and extend the life of transmissions. If your car is still under warranty, you should check with your dealer to make sure use of Lubeguard will not invalidate your coverage.

Lubeguard, made by International Lubricants Inc. of Seattle, has won endorsements from a wide range of expert mechanics and automotive publishers and is now recommended by half a dozen automobile manufacturers, including Volvo, Volkswagen, Subaru and Audi.


The product is derived from rapeseed and can withstand high-temperature conditions in transmissions that normally produce corrosive acids, said Frank Erickson, president of International Lubricants. The product was engineered to perform the same functions as sperm whale oil, a key component in transmission fluids until it was taken off the market in the late 1970s when the sperm whale was declared an endangered species.

Lubeguard can be found at professional transmission shops and selected auto supply stores.

*

Times staff writer Ralph Vartabedian cannot answer mail personally but will attempt to respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, 1875 I St. N.W., No. 1100, Washington, DC 20006.


Via e-mail: ralph.vartabedian@latimes.com.