Why should I replace my transmission fluid?

Today's transmissions are very sophisticated in the way they operate. They are computer controlled with electric solenoids to operate the gear changes, with electrically locking torque converters, which help improve fuel economy and performance. When repairs are required, they usually involve major work which can sometimes exceed $2,000.

The fluid performs four major functions:

  • Lubricates internal moving parts
  • Provides hydraulic pressure
  • Provides cooling
  • It is the catalyst to drive the torque converter

As the fluid ages, it becomes dirty and contaminated. The viscosity also deteriorates with mileage and use. When the viscosity is reduced, the hydraulic pressure in the transmission also decreases causing the transmission to work harder. The torque converter does not operate as efficiently which causes the fuel economy of the engine to drop off. This, in turn, will have an adverse effect on the clutch pak which, eventually, will lead to its failure.

How often should I replace my transmission fluid?

Most manufacturers recommend replacing the fluid every 30,000 miles. Some recommend less mileage, while others even higher mileage. We typically see a substantial degradation of the fluid around 30,000 miles. If you pull a trailer or use your vehicle to plow snow, you will need to change your fluid much sooner. We suggest that if you pull a trailer on a regular basis, you consider adding an auxiliary cooler to help cool the fluid. Stop and go driving, where the transmission is shifting a lot, is also hard on the fluid life.

Which method should I use to change my fluid?

There are several methods used to change automatic transmission fluid The most commonly used method is to remove the lower pan and change the filter. Another method is to drain the fluid from the pan without replacing the filter. The third method is to change the fluid while the engine is running (T-tech®). By changing it this way, you also change the fluid in the torque converter. Our technicians can help you decide which method is best for your vehicle.

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