Definitely do the valve stem seals. It might cure your oil loss problem. Like I said earlier, I went from adding a quart every 100-150 miles to not losing a drop. 7 of my 8 cylinders were leaking and one plug was fouled.
I've got my receipt in front of me. $52 in parts, 9 hrs labor. Total cost for me was $720.
1988 560SL Black/Palomino
1988 300SEL Black Pearl/Burgandy
1984 500SEC Anthracite Grey/Palomino