Possibly your oil filter housing gasket. If you go North of that item 6 location that's where the oil filter housing sits. Common occurrence. Did mine. Bit of a PITA but do-able for a novice.
Did mine before as well, not a difficult thing at all as there's so much space in the engine bay
The part number was 11421719855 and there's a decent how-to here; http://www.bimmerfest.com/forums/showthread.php?t=660007 the link is for an E46 however it's the same for us, just easier.