Do yourself (and car) a favor and do all 5. What I do is loosen it with a 12mm wrench, then if I can't turn it by hand after loosening a turn or 2, I can usually do alright with a mid-depth 1/4" drive socket. By mid-depth, I mean an inbetween-deep/shallow socket. A shallow will hit the end of the terminal end before it goes onto the hex, and a deep socket is too deep to work. Use this socket along with a universal "flex" adapter and about a 12" long 1/4" drive extension......Gilly