I thought that for the later model Mercedes they have a Fleece type Oil Filter for the exteded drian periods using synthetic Oil.

In any event if you are serious about your cleaning your Oil and getting the Max use out of the Oil in the Crankcase you should consider installing a Bypass Oil Filter system.
As, the Bypass filters filter down to around 1 micron; whereas, the full flow sections of Oil filters are somewhere in general are in the 20 something micron level.

While it is mosly for 123 Oil filters there is 3 sizeable Oil Threads with a lot of info.

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84 300D, 82 Volvo 244Gl Diesel