The black line is the vent for the tranny control -- it doesn't attach to anything under the dash, it is there rather than the engine compartment to keep dirt out of the vacuum system.

Oil gets in the vac lines from (usually) at leaking vacuum pump. When you shut the engine off, the vacuum in the lines will suck oil up, and eventually drag it all over the place. Very bad for the rubber bits, usually makes the sticky and soft. Oil can also get pulled in the shutoff, and once in the main line, everywhere else, too.

You can also get brake fluid in the brake booster, but I'm not sure that will migrate into the main vacuum system so easily -- would have to be quite a bit in there!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!