The MB black stuff is just a heavy duty industrial RTV. They also sell some orange stuff which is used on bolts into engine blocks on M119's and re-sealing things.
I like the orange sealant better than Hydamar. It is also sold by wurth. Never had a leak with it and it's nearly impossible to see after you wipe off the excess with a rag and a little brake cleaner.
Of course for timing covers... the corners get the RTV.


Michael