Piston rings are small bands or loops of metal that go around a piston in an engine. They help prevent oil from leaking into the combustion chamber and keep the fuel-air mixture contained, allowing the piston to move smoothly. Full definition
In the engine, components such as low - friction piston rings, a variable fuel pressure module, and upgraded software for the engine control module improve overall operation. (thekoreancarblog.com)
Without external evidence, high oil usage can be from worn piston rings allowing oil to be sucked into the cylinders and burned. (mechanics.stackexchange.com)
Most likely the problem is in piston rings or in the defective cylinder block. (mywikimotors.com)