Right you are Sean,
I just went to Pep boys and got an M10-1.5 and was able to put the nut on by
hand and tighten it with a 17 mm wrench. But I probably should have put on a
lock washer. Would you or anyone advise that I do? I don't see lock washers
on the other bolts but do see a regular washer.

Any thoughts (anyone) about whether or not my little drop of oil on the
bottom of the starter came from that loose bolt area which seemed to be wet
up top?

William Polowniak
1989 Vanagon GL
1988 Mercedes 300 SE