I have to write this fast before I go to my second Thanksgiving dinnner in 2 days.
Three things I'd like to add to the previous replies: 1)The (2)O-rings both fit onto the metal cap of the oil filter housing (lube them with clean oil before installing), 2)lay an old shop rag or several paper towels below the filter housing before you remove the cap to catch any old oil spillage, and 3) torque the filter housing bolt to spec with a torque wrench
When doing my 1995 S420, I use a 3/8-inch drive socket wrench and extension bar to get to the oil filter housing bolt, and a 3/8-inch drive torque wrench to reinstall. Sorry I don't have the torque figure here in front of me, and I don't want to give you a wrong number off the top of my head, but I can get it to you later if you don't have it. Oh, and have 2 oil drain pans to catch all the oil (8-plus quarts).