The automatic transmission fluid (ATF) for your vehicle is important and it helps in many features that will keep your vehicle running. It will clean, cool, lubricate, apply force, apply pressure, stop buildup, and consistently protect your automatic transmission.

When you come in for your regular oil services, our ASE-certified mechanics here at GIC Car Clinic in San Jose, California will inspect your ATF as well. Most vehicle manufacturers recommend that you have your transmission serviced at least every 30,000 miles. Depending on your vehicle make and model, the service intervals required may be different. Your owner's manual can provide you with the appropriate information, or you can contact GIC Car Clinic and we will provide you with any information needed on your vehicle.

Just like your car needs routine engine oil service, ATF needs to be changed as well. The fluid in your transmission needs to be changed regularly to keep it from breaking down over time. Transmission services are often neglected and even when performed, are often incomplete which will lead towards your transmission having complications with shifting or other transmission issues that will put strain on your vehicle. In the long run, this can lead towards premature transmission breakdowns and expensive repairs.

There are different methods to have your transmission serviced. The three most common methods are transmission fluid drain and refill, transmission pan gasket and filter replacement, and transmission flushes.

Typical transmission fluid drain and refill service:

  • Remove the transmission drain plug to remove the old ATF.
  • Re-install drain plug.
  • Refill the with new fluid to the proper level.
  • This service is very similar to an engine oil change. Advantage of this service is the low cost to perform. However, this transmission service generally replaces only about 3 quarts of ATF. A typical transmission fluid capacity is 8 to 12 quarts. The second the vehicle is started, the new fluid mixes with the old eliminating much of the benefit of the service.
  • Only some make model vehicles have a drain plug. Most older domestic cars and trucks do not have a drain plug.

Typical transmission pan gasket and filter service:

  • Removing the transmission fluid pan.
  • Discarding the old fluid.
  • Optionally replacing the filter. Some transmissions have metal screen filters which need to be clean not replace.
  • Replacing the transmission pan gasket. If your car has plastic/rubber gasket with metal core, they can be reused. Any other gaskets must be replaced.
  • Re-installing the transmission pan.
Typical transmission pan gasket and filter service | GIC Car Clinic
  • Adding ATF through the dipstick tube based on what your transmission requires. Typically you will require approximately 5 quarts of ATF. This level is normally indicated with a dipstick.
  • Check the transmission fluid level once the engine has been started and shift into all the gears to ensure it is at the appropriate level.
  • A pan gasket and filter transmission service will generally replace the fluid in the main body of the transmission only. Only about 40% of the contaminated and old fluid is replaced. The remaining 60% of the fluid is stuck inside the valve bodies, torque converter, and cooler lines. Most of the ATF remaining are in the torque converter. A few transmissions include a plug that you can use to drain the fluid from the torque converter. However, most transmissions need to be separated from the engine to be able to drain the torque converter. Removing the transmission just to drain the torque converter requires a lot of labor hours and not practical.

Typical transmission fluid flush

  • An automatic transmission flush consists of a complete exchange of fluids. A typical service requires 12 quarts of fluid and can extend to 20 quarts. This depends on how clean or dirty the fluid appears as well as what kind of vehicle you have.
  • When your transmission fluid is flushed, the pan for the fluid is not removed. The filter is not replaced either.
  • These flushes should eliminate some of the dirt and other particles from your filter.
  • A major benefit with a transmission flush as opposed to a pan gasket and filter service is that the torque converter and the rest of the transmission components will be flushed out with new fluid.
Typical transmission fluid flush | GIC Car Clinic

Automatic transmission flushes vs. pan gasket and filter transmission service:

  • Pan gasket and filter transmission services will replace the pan gasket as well as the filter.
  • Pan gasket and filter services will only remove and replace about 8 or 10 quarts of fluid. When the car is started, the newer ATF will mix with the old which negates the benefit of having the service done.
  • The pan gasket and filter transmission service may provide knowledge of transmission problems within the engine based on any excessive metals within the transmission pan.
  • The transmission flush will remove and replace all of the fluids.
  • The transmission flush will not replace the filter.
  • The manufacturer of your vehicle may not recommend a transmission flush.
Our State-of-the-Art Transmission flush machine | GIC Car Clinic

Our State-of-the-Art Transmission flush machine

GIC Car Clinic's transmission flush machine replaces virtually 100% of the used ATF. Our State-of-the-art transmission flush machine does not use pressure. Instead, it uses the transmission's own pump to move in the new fluid that displaces the old fluid. Our machine will make sure that the sludge and other various deposits are removed safely from your transmission and its components.

Our latest Transmission flush equipment shown here on YouTube
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