I am certainly not an expert on your particular model, but I hope you will let me share a little of the meager knowledge I have stumbled across. On most MBs if you are a very diligent owner and insist on keeping the oil exactly to the full line the engine almost always brings the level down to about midway. If you can force yourself to be content to just monitor the level and not add more oil uless it goes below the minimum most engines in good condition will seek their own level and happily stay there until it is time to change. For many owners this is a lot to ask, but grit your teeth and give it a try. I love my cars too, especially their precision, but the oil doesn't have to be at the top mark to be perfect.

Bob DuPuy
1971 220D
1983 300SD