Originally Posted by Tone
A flush is the ONLY way to get all the fluid changed out in a tranny - all 9.1 qts. A drain and refill only gets about 3-4 qts out and leaves the majority of the old fluid in. Dropping the pan and changing the filter gets the same amount but should be done every other change IMHO and is good to do after flushing with synthetic since that fluid has a longer life. Although it is a chore, the filter will not clean itself and a clogged filter will eventually kill the tranny.