for Experts, oil leakage M3

Hi , i got an Euro M3 E36 and i have a little problem, my engine leaks some oil from a conical screw situated in the 6th cilinder... I try to explain to you where the screw is located; when I'm under my car (under the gearbox for example) looking forward in headlights direction this screw is on the right side of the engine, just under the 6th cilynder emplacement(with 6th cilynder i mean the one closer to the gearbox). it's a screw with a cut for a flat screwdriver, the head is about 15mm large... Now at my local BMW dealer in Italy they told me that they are not capable to find me the spare, do you kow where to find it or how to solve this problem?? Many thanks! Massimo Visconti P.S. to John Burns, glad to meet you man, i visited all of your site, you got a Great car (the 6er)!!