Well i have the same prob, ive engine shampooed it once and forgot about it for a few weeks and it was back, nothing serious drips a lil oil lol, i looked at my valley and turbo now theres no "wet oil" but more like dried up ive never been cleaned oil, the wet oil looks to be coming from the rear main which ive seen alot of up here ( canada ) ill was my truck again tonight at the shop see if anything shows up next day or 2 but im betting its the rear main. for me anyways.