burning oil. your compression rings are also bad..
compression is what makes the power
spark plug fouling... and not just One... and each one is a LOSS of 15 percent of power...
extremely bad gas mileage. as the oil reduces the energy of the gasoline.
air pollution. ground and water pollution.. from venting and tail pipe drops.
plugging of catalytic converter or 2... and when it does happen.. expect less then 20 miles per hour drive home. if you make it.
other things that make an engine burn oil
bad PCV
bad intake manifold gasket
bad EGR valve
bad Air pump (if equipped)
bad valve guides and seals.
and in some designs cylinder head gaskets.