There are no AT experts here or at a dealership. The reason to add 2 quarts at a time when you flush, is because you are flushing 2 quarts at a time. Because you are around 4 quarts low at this point, I would add 3 quarts. The tranny pump runs with engine rpm, so start the engine for a minute or two, shut it down, and check the level on the cold side.

Your tranny will not be hurt if you are 2 quarts low. I suggest not driving it with more than a quart missing - I was down 2 quarts and drove a lot until it got cold out and the torque converter started making terrible noise. The previous owner filled the tranny to the 'full' mark with the engine off and fluid cold!

You could probably do the same as my previous owner. Without starting the engine, fill the tranny with ATF until it gets to the full mark, then add an additional quart of ATF. That should put everything pretty close, then after the engine is running and you have selected every gear for a few seconds, you can check the level with the engine running and top it off.

So long as the pump has enough fluid so it does not cavitate and create foam, you are in good shape.
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