Actress Hailee Steinfeld pairs a navy-and-white dress with white strapped sandals at an event in Los Angeles in 2013.
If the oil is on the inside parts of the spark plug like the bottom insulator, that's a bigger issue, you have either leaking valve seals or very leaky piston rings. If your car blows a puff of blue smoke on startup, you probably ave leaky valve seals. If it blows blue smoke all the time, leaky piston rings.
When oil leaks from the main seal, it usually occurs at the connecting point between the engine and transmission. Therefore, to gain access to the rear main seal, a mechanic will usually have to remove parts of the transmission and nearby components.