What happens when piston rings have worn out?

What happens when piston rings have worn out?
well wen piston rings go u will have to change them to be safe i would change the rods and valves to,just to be on the safe side.Answer:The engine will loose power, increase fuel use, increase pollution creation and use oil faster than normal.
As the problem progresses the engine will become hard to start and blue smoke will come from the exhaust.
Inside the engine the failing rings will allow more combustion products into the crank case causing the oil to loose effectiveness faster and speeding wear on other components.