The first tep is to find the owners manual, It will show where the dip stick is. The next step is to use the hose from the topsider all the way down to the pan. It will get out all the oil, dont fool with the oil filter since there are check valves in that. It should be at the front of the engine, the trans is at the rear.
MB is competive on oil changes my last change was $100 synth, and genuine filter, plus a wash. I dont go for the A or B just change the oil and filter if you want to save money.
I dont think just because it is a lease it does not need to be taken care of