This video will show you how to do and oil and filter change on Mercedes C220 CDi BlueEfficiency W204 OM651 engine. Some procedures may differ for other models, please check carefully the oil spec and oil capacity for your particular car.
For this particular car I used 6.5 litre of 5W30 engine oil, spec: 229.51, this is Suitable for W204 CClass C200 C220 and C250 CDI OM651 Diesel Engines.

Steps:

Oil and Filter
1. Remove engine top cover, by simply pulling it up to access the oil and air filter
2. Remove the bottom cover which is hold in place by 11 bolts/screws
3. Locate drain plug and put a catch pan underneath
4. Take out the drain plug and wait for the oil to drain.
5. Watch the oil flow at the draining point and adjust the catch pan accordinglly.
6. Take out the oil filter housing
7. Pull out the oil filter cartridge and old O rings
8. Install the new O rings and oil filter housing
9. Lube the O rings with a bit of fresh oil, this will reduce friction when you install the filter back on the engine
10. Screw the filter housing back on the engine
11. Replce crash washer on the drain plug, fit it back and tighten it up
12. Poor the oil into the engine
13. Go back under the car and check for leaks.
14. Fix the bottom cover back

Air Filter
1. Pull out the wiring loom located on the right side of the air filter housing, to expose the hidden screw
2. Unscrew the all 7 screws
3. Take the cover out
4. Take the old filter out
5. Clen the air filter tray, make shore to not blow any debris on the maff/mass air sensor
6. Fit the new air filter, make shore is fully inserted and secured into it's slot
7. Fit the cover back and tighten up the screws
8. Clip the wiring loom in it's place

Next step is to reset the service warning light from the dashboard. Please check the link below for instructions.

Related videos
How to reset service warning light:    • How to Reset Service Light, Service M...  
How to replace cabin filter:    • How to replace the cabin filter ac fi...