Some vehicle manufacturers require an automatic transmission service as part of a routine vehicle maintenance. An automatic transmission service is usually required to be performed at certain mileage intervals. In the past, most manufacturers say it should be done every 30,000 miles.
With some of the newer vehicles it’s suggested at a higher mile interval, sometimes as high as 100,000 miles and in some cases not at all.
Typical Automatic Transmission Service
When the typical automatic transmission service is performed it usually entails the following procedure.
- Remove transmission fluid pan and discard old fluid.
- Replace transmission filter (optional). Many transmissions have metal screen filters and some have paper screens. Metal screens don’t need to be replaced.
- Replace transmission fluid pan gasket. Some rubber gaskets can be reused. Cork gaskets should be replaced.
- Reinstall transmission fluid pan.
- Add transmission fluid, usually through the indicator (dipstick) tube. The average fluid is about 5 quarts of fluid. Some transmission will vary.
- Start engine and check transmission fluid level to insure it’s at the proper level.
Performing the typical automatic transmission service usually only replaces the fluid in the body of the transmission. There’s still a large amount of fluid in the torque converter. Some transmissions have a plug where the fluid can be drained from the torque converter. The majority of transmissions must be separated from the engine in order to drain the torque converter and can be labor intensive.
Typical Automatic Transmission Flush
The typical automatic transmission flush is a complete fluid exchange. A pressurized flush machine forces the old fluid out. Usually a cleaning agent is introduced to clean internal parts of the transmission. Since the flush machine is pressurized, the machine might pick up internal problems with the transmission, if there are any. The average transmission holds about 12 quarts of transmission fluid.
When the automatic transmission is flushed, the transmission fluid pan is not removed; therefore the transmission filter is not replaced. The pressure of the flush should remove most particles from the transmission filter. One big advantage to a transmission flush versus a service is the torque converter fluid is replaced with new fluid.
Automatic Transmission Flush vs. Transmission Service
- A flush removes and replaces all fluids, a service usually doesn’t.
- A flush can blow out a seal because it’s pressurized, a service won’t.
- The vehicle manufacturer might not recommend a flush.
- A flush may indicate internal transmission problems through pressurization.
- A service may indicate internal transmission problems by excessive metal in the trans fluid pan.
If a person is apprehensive about performing an automatic transmission flush instead of a service, ask the auto shop if there are any guarantees. Some transmission flush companies, that supply the machines and products to the auto shop, may warranty the transmission. There will be stipulations to the warranty like a requirement to flush the transmission at certain mileage intervals. If they offer a transmission warranty along with the flush, always get the warranty in writing.
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