Oil in the lines is often from the "shutdown valve" on the rear of the injection pump. It's brown tube runs to a vacuum switch at the "ignition key". Another brown tube runs to the main vacuum source. Don't mix up the two tubes (colored stripes, forget which). Best to plumb a small clear filter in-line w/ the shut-down valve so you can see when its rubber diaphragm fails and sucks oil thru. That is better than waiting until oil drips on your right foot. You can buy such filters as fuel filters for lawnmowers. Some VW shops keep them in bins. A similar clear filter is factory, in the black vent tube between the cabin and the VCV (on top of IP).

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans