Piston rings are seals that help contain the explosive force when gasoline is ignited inside the cylinder. Sticky piston rings are caused by poor maintenance. Carbon builds around the grooves in the piston, where the rings fit, seizing them to the piston. When this happens, the rings cannot seal properly against the cylinder wall. In addition to sealing the explosion, they also keep oil out of the combustion chamber. When rings stick, the engine grows weaker and starts to burn engine oil.
Raise the bonnet of your car and use a socket wrench to remove all of the spark plugs. If necessary, label all of the spark plug wires with a piece of masking tape to prevent mix-up when they're reinstalled.
Fit a solvent-resistant hose into one of the spark plug holes. Push a funnel into the other end and pour 113 to 170gr of engine flush directly into the cylinder. Repeat this process for each cylinder. Push a paper towel into each spark plug hole and let the solvent set and work overnight.
Remove the fuse cover from the power centre located under the bonnet and remove the engine computer fuse to disable the fuel pump and ignition system.
Turn the ignition key on and off to "bump" the starter. This will push the solvent out of the spark plug holes, and the paper towel will capture the liquid. A large amount of solvent will have leaked past the rings and into the oil. Jack up the car, place jack stands under the frame and use a socket wrench and an oil filter wrench to change the oil and filter.
Remove the paper towelling from the plug holes. Reinstall the spark plugs, add fresh engine oil and replace the computer fuse. Start the engine.
It may be necessary to repeat the entire process if the rings are severely stuck. In some cases the rings cannot be cleaned by this process, and the engine will require an overhaul.
The engine will smoke until the solvent burns away.