Keeping Metal From Contacting Metal
I've never heard of oil needing to be broken in. This is why you change oil in the first place, to keep it fresh, clean and new. Oil is designed to keep friction and metal to metal contact at a minimum. After you change the oil in your Benz and start the engine, the oil starts to break down.....slowly but it eventually does break down.
I change the oil in my 240D every 1500 miles with Mobil Delvac 1300....Maybe changed too often but I believe in removing all the soot and impurities from inside the engine as much as possible to have the engine operate in the cleanest oil possible. I change it hot and often per Larry's motto.
If oil needed to be broken in, we would never change our oil.