* Spark plugs are *inside* the combustion chamber. They're not directly exposed to the coolant or oil systems. Any leak appearing *around* the spark plug indicates a breach in the engine's structural integrity.
* Cracked Engine Block or Cylinder Head: This is the most likely culprit. A crack in either the block or head can allow coolant or oil to seep into the combustion chamber. The pressure from the combustion process can then force fluids out around the spark plug, where it's easiest to escape.
* Head Gasket Failure: A blown or severely damaged head gasket is another serious possibility. This gasket seals the area between the engine block and cylinder head, preventing coolant and oil from mixing. A breach in the gasket near a spark plug well could allow leakage. This is less likely to cause oil to leak *directly* around the plug itself compared to a crack, but it's possible for pressure to force it that way.
It's crucial to note: This is not a DIY repair. A leak of this nature requires a professional mechanic's assessment and likely significant engine repair or replacement. Continuing to drive the vehicle could cause catastrophic engine damage. The cost of ignoring this will likely far exceed the cost of proper diagnosis and repair.
