"Lakelover" : If you check the Maintenance Manual and refer to the section on oil changes, there is a drawing of the special adaptor used by MB to suck the oil from the engine via the dipstick tube. That drawing shows that the adaptor and suction tube are only inserted into the top flare of the dipstick tube, about two inches. The dipstick tube evidently goes right to the bottom of the oil pan, or close enough, so suction applied at the top of the dipstick tube is enough to draw out all the hot, hot oil.
Rather than try to purchase the elegant adaptor used by MB, I purchased a length of 3/8 inch I.D. transparent, braided, PVC tube from Home Depot. The O.D. is about 1/2 inch and fits easily but snugly into the flared portion of the dipstick tube. I connected that back to the container for collecting the hot, hot oil and that container in turn is connected to a vacuum source. The oil filter cover is first removed, then the vacuum is applied. Yesterday was my fourth experience using this method and the measured volume of the oil removed was 7+ liters....I am satisfied that I removed all that was in there and it took about 15 minutes, with no mess.