Try a search for turbo oil drain. There is a grommet down there, but it is a pain to get it apart. I'm cutting out the middle of that tube today and replacing it with some hydraulic hose to fix my leak and make future servicing easier.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine