Do yourself a favor and do the hardest ones first so you are the most relaxed and take your time, put it in straight, when the spark plug stops, you stop.
I always put just a little antisieze on them because I dont want to pull the threads out.
No Benzes in the stable at the moment, but itching for one again.
Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 300E Amg Hammer 88k mi sold
1992 500E 156k mi sold