On ML vehicles, it is recommended that oil be sucked out as the drain below is above the sway which causes oil splatter all over the bushings which can degrade with exposure to oil. On your e320 with a m112 motor, you can remove the plastic belly pan below. It is held in place with a few 8mm screws. Then undo the bolt and drain the oil. It will help if you get a set of ramps. To remove the filter assy, you will need a special cup tool that fits over the filter assy. Once you get the assy out, remove the filter element along with all the rubber o-rings. Replace those o-rings with new ones that come with the filter kit. THe engine holds approx 8.5 quarts of oil.