I have a VP 5.0 GL. The power steering pump weeps fluid which makes the bilge water oily. I probably take on a gallon of water per day into the bilge when the boat is in the water. When the boat is stopped and sitting in calm water an oily film eminates from the area of the stern drive (Cobra SX). Is this likely a leaky bellows? And if so, which bellows is the likely culprit?