Mercedes: changing oil/filter on a MB 2007 E320bluetec, hex key, mechanical supply

Question
I just started changing my oil in the car. The amount of oil that the engine takes
is 9 quarts? I believe the oil filter canister is under the hood at the front Left
side of the car, it is secured with a hex key? where do I get the hex key?

Answer
Tim,
If this is a canister type of holder, it is hexagonal like and 'allen wrench' you should measure the distance across the opening in mm and pick up a wrench at the mechanical supply or parts house. Otherwise this may be a dealer $$$$$ item.
Good Luck
Rob