Originally Posted by syfi

The filter fits many different models, some of which require the additional o-ring. Ours always have a left over one. Uses only 4 rings. Also, invest in an oil evacuator, such as the Mityvac 7201. Easiest, cleanest and most effective way to change oil, and it's the recommended way by Mercedes (it's how they do it at all dealerships). The 3.2 liter motors were designed to use evacuators exclusively!

Mityvac 7201 Fluid Dispense/ Evac - Lubrication / Hose Reels