There is not a drain on the torque converter. Figure you're leaving 1-2L of original fluid in there when you just drain the fluid. Some like to do the multi-drain process to get to one fluid, which seems an expensive way to go. I used OEM fluid (VW version through discounting VW dealer), so that wasn't a concern. If you are going to do a multi-drain process, you might consider whether it's worthwhile to drain the lines to the oil cooler. Can't comment on ease or pain of doing that.