Reading spark plugs can give some very detailed signs about your engine condition, individual cylinders, tuning etc. Any oil fowled plug(s) will indicate probable blow-by via the engine piston rings or valve guides consequently causing your turbocharger to leak oil. A damaged spark plug(s) can cause impact damage to the turbine wheel from the debris exiting via the exhaust valve causing imbalance and eventual turbocharger failure. Remove your spark plugs and check them against this chart. Please click on the image to enlarge it!