The Oil Filter housing is on the Drivers side of the Engine its a Black Round cover..To Remove Unscrew Counterclock wise
Make sure you replace all the seals/o rings on the cover when changing the oil filter...I Use a TOPSIDER oil change tank..that sucks the oil out of the dipstick..It works great
The Mobil One is very good I also change the oil in both of my Mercedes @3,000 Miles With Mobile One...Maintence is Cheap......
Interested in any Performance Mods?

Good Luck with the SLK!!