What is the black hose / tube along the right side of the engine, beneath the oil filter, along the ledge called? I think it is leaking oil, but not much. Started the car this afternoon, let it warm up. When I checked the oil, I noticed the oil on the ledge. The oil is right where it is suppose to be. On the floor in the garage is a thin line of oil, no puddle. Can the 911 be driven? Is it an ordinary Porsche oil leak?

Thank you,