E350 oil change with Mityvac
 

Changed the oil yesterday using a Mitivac 7201 for the first time on this vehicle and was only able to get 5 liters out. Typically I use ramps and get underneath, I'd be interested in hearing others experience here with oil extraction.

Do a search here for Mityvac and you'll find some had more success with sealing the engine dipstick tube around the suction plastic tube. So the engine tube becomes part of the suction tool so to speak.

x2 on using engine tube.
The big Mityvac tube with some pressure does seal in engine tube funnel neck and that is how I was using it.
I think engine tube has small venting hole on it somewhere in crankcase, so you will get some gargling, but still should go easy.
Per my observation MB puts dipstick tubes in the corners of oil pans, so I observe it, and try to park with this corner at lower point, or even put planks under wheels to make it lower.
Lately, when friend "borrow" my Mityvac, I bought electric pump. Cheap and takes less storage, although more potential for creating mess.

You have a 4WD vehicle. There is another recent thread covering how to get the siphon tube around the shaft that runs through the oil pan on 4WD cars.

Compare the length of the inserted vac tube with the stock dipstick. That will give you a pretty good indication of how far you are getting into the pan.

I believe the dipstick tube goes down to the rear of the driveshaft. I need to look but that's what I remember.
I've not had an issue with my 4matic getting oil out using the suction tube seal to dipstick method.