Got under the car today to try and figure out the best way to remove the transmission fill plug after having some trouble last time. Although I didn’t actually remove the plug, I ended up using a 3/8‘s drive ratchet with an 8“ or longer extension and a 17mm shallow swivel socket. That ended up being the easiest way for me to reach the plug for future removal. I also tried touching the plug with my hand to see if I would be able to reinstall the plug by hand, but I couldn‘t quite reach it. I tried a snap-on ratcheting box end flex head wrench, but couldn’t get it to seat properly because of some metal protrusions around the fill plug. I was also able to reach the plug with a 3/8’s drive flex head ratchet and a 17mm low profile snap-on socket, but that was a bit more difficult and didn’t work as well as the extension and swivel socket. I also ended up turning the wheels both directions to see if that would allow more room, but that didn’t really help. Lastly, I tried reaching the plug from the drivers side wheel well. I turned the wheel completely to the right and was able to see the fill plug. I believe with a wobble extension and socket or extension with a swivel socket, you should be able to remove the plug if you remove the wheel to give you some room to work with.
My understanding for the DCT transmission fluid you should have it checked every 40k mileage depending on your driving conditions. It didn't even mention replacing in my owners manual other than having it checked and IMO that doesn't sounds all that good. It should be replaced probably around the 40K mark. I'm guessing it depends upon how hard we drive our cars.
I cracked open the 8mm hex fill bolt after attempting to do the proper fill hole. No way can I at my age do this with the fill and check hole. It's a tough bolt to turn but she came loose. I drained about 2 quarts out and same back in with redline . Mine is a 2018 Elantra GT Sport with DCT.