What are the methods for changing automatic transmission fluid?
2 Answers
There are two methods for changing automatic transmission fluid: the gravity drain method and the flush method. Below are detailed introductions to these two methods: 1. Gravity Drain Method: This method leaves more residual old transmission fluid. The reason for this significant residue is directly related to the complex internal design structure of automatic transmissions. Typically, a common automatic transmission retains at least six to eight liters of old fluid, with about 50% of the total fluid remaining in components like the valve body module and torque converter. Additionally, the design of some transmission pans also contributes to fluid retention. 2. Flush Method: The flush method is more complex than the gravity drain method. The complexity lies in combining the flush method with the gravity drain method. Beyond the equal exchange performed by the flush machine, some automatic transmissions require not only an initial gravity drain but also the removal of the transmission pan to replace the filter for a more thorough cleaning. Every step before, during, and after the fluid change must be executed flawlessly. In simpler terms, this method demands higher technical precision in the replacement process.
I think changing the transmission fluid isn't actually difficult and can be done by yourself. First, park the car on a level surface and engage the handbrake to prevent rolling. Then gather some tools, like a jack to lift the car and securely support it with jack stands. Crawl under the car, locate the transmission drain plug, and use a wrench to loosen it, allowing the old fluid to drain into a large container. Once the fluid has fully drained, tighten the plug back without over-tightening. Some models also have a transmission filter that needs to be removed and replaced to prevent clogging. Next, add new fluid—preferably the correct specification as per the owner's manual—and avoid mixing different types. Use a funnel to slowly pour the fluid into the fill port, start the car to let it circulate, and then check the dipstick to ensure the fluid level is correct. The whole process takes about 20 minutes, but remember to wear gloves and safety glasses. Dispose of the old fluid properly by taking it to a recycling center—don't pour it down the drain. Regularly changing the fluid this way can extend the transmission's lifespan, prevent overheating and wear, and ensure smoother driving.
