Dang... I'm glad I just read the whole thread. I was about to suggest the distributor o-ring myself because both of the sensors below the distributor are really for coolant. The oil stuff is on the back of a D15B7.. Oil follows gravity, and that's a very common oil leak on any Honda. Mine even just started doing it and I only have 20k on a brand new o-ring. Get a few spares, they only cost pennies.