Originally Posted By: unDummy
Start with a drain/refill or pan drop 1st and top off. Perform your flush with 10+ quarts of your favorite ATF depending on your 'budget' and ATF chosen. And be done with it.
For anyone that wants to know why more is better, take a 12 ounce empty glass, add 1 ounce of milk(your dirty ATF), put glass with milk into a container in your sink, slowly run your tap until that milk is overflowed out and nothing but clear water is left in your glass. Now, measure the amount of the milky container's water that your glass overflowed into.
This is why I drain/refill my ATF pan at relatively short intervals, like at every or 2nd oil change, or minimally once a year within reasonable mileage/cost intervals.
Once I flush to a fluid I am 100% comfortable with, I then hope to drain/fill with the same fluid every other oil change or so.