Discovered the exact same thing today on my 530, I changed plugs as well and there was oil, only in one plug well though. I put in the +4 as well, seems to be running smoother. how difficult is it to change the gaskets?? one thing I have learned is that BMW can make things insanly simple, or insanly complex so excuse the question. Does anyone know of a site that explains the procedure. I already have the bentley book and i really dont find it all that great. Thanks