So my 4l80e has a drain plug on it (GM love the stupid T55 Torx that just strip out). Well it wont budge. I am planning on eventually taking off the pan to switch out the filter (question on that in a minute), but wasnt going to do it right now. I was going to drain and fill (about 8qts) drive for a little then repeat at that point giving it about a 75-80% new fluid (even though 16 quarts had been put in) since it is mixing with the old fluid that is in the torque converter. On the second time is when I was going to switch out the filter. I did some penetrating oil and heated it some, didnt want to do too much as I dont want to mess up the aluminum (i think) pan. I am going to try and use an impact gun slowly increasing the torque as I can adjust my gun, but once again dont want to mess up the pan. As far as the filter. what do you all recommend. they have the basic kits with filter and cork gasket. found one that is premium filter and a coated metal (oe style) gasket at about $70 or just the filter with gasket maker. Do some of you just swap out filter and use gasket maker or just buy the cheap gasket. Looking for what seems to be the best for not having a leak afterwards but if just a gasket is leak proof enough that is a little cleaner.