I planned on having the ATF filter and fluid replaced replaced at 44000 miles by the dealer. I just noticed that there appears to be a drain plug recessed into in the ATF pan. It is a plug with either a Torx or Allen head bolt, Does the filter need to be changed, or can I drain the fluid from the pan and replace with the same volume and buy the ATF filler cap? Or is this drain I see not for removing the ATF?