http://www.amazon.com/Milwaukee-2300-20-M-Spector-Digital-Inspection/dp/B001AOVBHG

notice how the price has come down

on inspecting for the source of oil
you would snake into the valve cover looking at intake valve stem seals that might have pop'ed up,
and then snake into the combustion chambers looking upward at intake valves in both the closed and partially open positions by carefully turning the crankshaft ... but don't let the piston crush the camera !