Piston Rings

What it does

Each cylinder in your engine has a piston that shoots up and down thousands of times a minute. Around each piston are rings — thin metal bands that press against the cylinder wall to do two jobs: keep the compressed combustion gases above the piston (for power), and scrape oil back down off the cylinder walls (to keep oil out of the combustion chamber). When these rings wear down and lose their spring, they can't seal properly. Combustion pressure escapes (loss of power), and oil gets pulled up past the rings and burned (blue smoke). Piston ring replacement requires taking the engine apart — it's a major mechanical job, but often the only real fix for high oil consumption from internal wear.