Your oil leak is most likely the o-ring between the Oil Cooler Adapter and the block. There is also another o-ring at the filter end, but the block side always leaks first in my experience. It is not a bad job to replace. Do it at your next oil change. By the way, we own three 740Ts, and while all have had an oil leak at one time or another, there are no oil leaks off any of the three cars and the driveway and garage floor is clean under them.