I would also add that being a little bit low is way better than being a little bit high on the oil level. Being a little high allows the crank balancers to splash in the oil, which causes the oil to foam, which in turn lowers the oil's ability to lubricate.
That said, I've seen many engines that when filled to the full line will use just enough oil to drop the level mid way between the max/min lines, then not use a drop after. Most MB dipsticks have about a 2 quart/litre capacity between the marks.
1 quart usage in 3K miles is well within the acceptable limits for these cars. That is just about what I see on the 560 with 185K.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.