83 300SD has an electronic oil pressure sending unit, so the line to the instrument panel would not leak, unlike a 123, which has a direct sensor and can leak. The sending unit could leak. Other alternatives are the oil filter housing to engine block gasket, but I would favor the oil-filter housing to turbocharger oil supply line. They can get brittle and break. They are sort of a pain to replace.

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Der Panzermann und Fraulein Fahrvergnuegen

1991 420SEL 201K "The Big Blue One"
1985 300DT 205K chassis/285K engine nee California emissions "Goldbug"
1983 300TDT 255K "The Womble"
1983 300 DT 214K "Sea Sprite"-Rear-ended a truck
1983 300SD 285K "The Donor" Gave his life so that others can live
1980 500SL Euro 105K "Der Panzer"