The Difference Between a Transmission Flush and Transmission Drain / Refill

When it comes to changing your transmission fluid, there are two common ways of doing it. One way is sometimes referred to as the drain and refill method. The other is called a transmission flush.

Transmission Drain and Refill

The drain and refill method is done by draining the transmission fluid from the drain plug. Sometimes there is no drain plug on the vehicle and needs to be drained from the transmission pan. Then once drained, refill the transmission with new transmission fluid. Another thing to consider is some vehicles have a transmission fluid filter which also needs to be changed during the drain and refill process.

Transmission Flush

 The transmission flush process is typically done by a professional transmission repair shop. The transmission repair professional uses a transmission flush machine that is hooked up to one of the transmission fluid cooler lines. While having the engine run, the transmission flush machine gradually pumps the old transmission fluid out and replaces it with new fluid at the same time.

What method is better?

Each method is effective in it's own way. Good information to know is when using the drain and refill method you are only able to replace 40 to 50% of the transmission fluid during the process. Much of the fluid is trapped in the valve body, torque converter and other parts of the transmission which makes it impossible to drain the fluid entirely. The transmission flush method allows you to change approximately 90 to 95% of the fluid. It is suggested to refer to the vehicle's owners manual, some vehicles do not recommend the transmission flush method and only recommend the drain and fill. Typically it is safe to use the transmission flush method on vehicles with lower miles and the drain and fill method on vehicles with higher miles. It's recommended that both methods be done by a transmission repair specialist. If you are in need of any transmission work in the Southeast South Dakota area. ask the professionals at Jim's Transmission.