At least one of our Members with the same style of Fuel Supply Pump claimed that the Tiny O-ring that Seals the Push Rod was the source of his Oil Consumption.
He felt the Oil from inside of the Fuel Injection Pump was gettend sucked past the O-ring and mixing with the Fuel and ending up burned in the Engine.

I do not recall if he rebuilt or replaced the Fuel Supply Pump but; said that it fixed the problem.
Besides the Oil consumpiton issue the other symptom is that his Fuel was getting grey colored from the Engine Oil.

__________________
84 300D, 82 Volvo 244Gl Diesel