I've got an 82 240 D w/ good compression that will smoke at startup and then stop smoking till you rev it. It can use a quart of oil in 2 hours if you drive that 2 hours at 70. Much less if you drive slower. I was thinking valve seals.
Also, do you get what you pay for w/ Kent Bergsma's parts kit & how to on 240 D valve seal replacement? $50 is steep when I don't need the new valve cover seal, and the seals themselves are about $10.