Amsoil is probably the best you can get IMO, especially if you want to do it one time and forget about it for a while, but I just use Dexron VI, and do a drain and fill about ever 30k miles, (40-45k miles will work also). Have never had any issues. No need to flush as long as you use Dex VI. If I were going to use Amsoil, I would pump out all the Dex VI in the tranny using the procedure that is on this forum, before adding Amsoil. I think you will need 12-16 quarts of Amsoil to do a proper flush and fill. No big deal draining and refilling these tranny's. Takes me about 10-15 minutes. Just put back in what you drain out, that way it is always at the right level, unless you have a tranny leak. For me it is exactly 4.5 quarts every time I drain it. Now the way I do it does not get all the fluid out at one time, only about a 1/3 of it, as the whole system holds about 12 quarts if memory serves me. By doing it my way it still does a good job, as every 30k miles 4.5 quarts of older fluid is replaced with 4.5 quarts of new. Since it is so easy, I will continue to use the Dex VI fluid as I have been. Lots of different ideas on how to properly do a tranny fluid change on these cars on here, but several do it my way, and none of us have ever had a tranny problem. I do this with my 08' Honda Civic also, just drain and refill with Honda tranny fluid only. I've done it every 20-25k miles, and this is even what the manual states to do with it. It is right at 3 quarts every time I do it. Never an issue with it either.