You can also use the Zerex G-05 that is available at most AutoZones now. It is the exact same formula that Mercedes has been selling for a while now and is a lot less expensive. And yes I confirmed this via e-mail with the Valvoline Corporation.

To help further your draining endeavors, remove the black hose just above the airpump, that will drain your heater core and the residual fluid from your water pump. I don't have a picture to help you out but if you follow the metal tube across the front of the engine (one end attaches below the thermostat housing and the other to the black anti-freeze hose), that's the one!!

I usually get about a quart of fluid out of it when I disconnect it.

Good luck,

Dale