When I flush an automatic tranny I simply disconnect the return line from the cooler and drain there with the engine running, adding fluid at the same time. Tends to take me about 2-3 gallons this way. Big difference is I get the fluid hiding in the torque converter that doesn't get changed when you just drain the pan.

Draining just the pan, you only change about 1/3-1/2 the fluid.

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anyone used the BG product when flushing transmission? Seems most of the shops here want to do a flush using BG products. Any comments?