Not specific to your Vehicle but from what I have read People who drive their Vehicles locally had no Oil level issues till they went on a long trip on the Freeway/Expressway.

Apparently hours on the Freeway/Expressway consume Oil Faster.

A few People have calimed when the little O-ring in the Fuel Supply/Lift Pump gets bad enough it sucks Oil from the Fuel Injection Pump. Since the Oil Fuel is Injected it burns well and is not noticed except for the Oil comsumption issue.

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84 300D, 82 Volvo 244Gl Diesel