I think that it is GREAT for anyone who owns a car to know how to service it. I have TAUGHT both of my Daughters how to service their cars. They now do it with me watching.
My BEST suggestion would be to find either someone in this site or a trusted mechanic to "walk" you through a complete oil change and service. While the Mercedes isn't a complicated car to service, it is EXPENSIVE if you do something wrong. Point in fact, I saw a perfectly good '69 250S engine turned to junk because this guy over-tightened the oil filter canister, unknowingly cracked the top and ran it until it quit. The cam was siezed in the head as well as the bearings were gone in the lower-end.
Find someone good, offer to pay them for their talent and learn the RIGHT WAY to do it.
If you live on the central coast of calif, PM me and I will help you. Chris

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.