Just dropping the pan and filter is only part of the transmission fluid in your system. The rest is floating around inside the transmission itself and in the torque converter.
Well, this is true, but using a drain bolt isn't going to remove any more fluid than dropping the pan, and doing a flush then dropping the pan and changing the filter is going to do a lot more of a complete job then draining the pan. I think I end up putting about 3.5 quarts back in out of an 8.8 quart fill, let's call it a 40% ATF change if you just swap out what's in the pan.
So humor me for a minute, and I'll explain why I don't see that as practical. Your first pan drain and fill you've changed 40% of the ATF, leaving 60% of the old ATF. Do it twice, and you've taken out the now mixed together 60% old ATF and 40% new ATF for an overall 64% change. Three times is a 78% change. You're always mixing old and new fluid, so you're always going to have the old stuff floating around. The good news is by the 10th change you'll have diluted the original fluid to below 1%, which if you're on the 3k mile oil change schedule is right about the same time I'll be doing another flush and filter change. :gr_grin:
Plus, you've never changed the filter. Plus, while I'm don't know whether or not you'll be able to get away without needing a quick learn for each change, I'm not sure I'd bet my transmission on it. I smashed the transmission pan and swapped it out at less than 20k miles and topped off the ATF, and it was not happy until I took it in for a quick learn.
Is the learn flash just removing the battery terminals for 30 min or is there something else to it?
Nope, you'll need to take it to the dealer (or someone who has a Starscan unit) and get it done. I think the dealer changed me $85 to get it done.