* Worn Piston Rings: Piston rings seal the gap between the pistons and the cylinder walls. If these rings wear out or become damaged (e.g., from lack of oil changes, using the wrong oil viscosity, or overheating), they can't effectively seal the combustion chamber, allowing oil to seep past and burn. This is a very common cause.
* Worn Valve Guides or Valve Stem Seals: These components prevent oil from leaking down the valve stems into the combustion chamber. Wear and tear can lead to leakage and oil consumption.
* Worn Cylinder Walls: Over time, cylinder walls can become scored or worn, creating gaps that allow oil to pass into the combustion chamber.
* Breather System Problems: The engine's breather system vents gases and vapors. If this system becomes clogged or malfunctioning, it can create excessive crankcase pressure, forcing oil past seals and into the combustion chamber.
* PCV Valve Problems: The Positive Crankcase Ventilation (PCV) valve plays a key role in the breather system. A faulty PCV valve can cause similar problems as a clogged breather system.
* Leaking Head Gasket: A blown or leaking head gasket can allow coolant or oil to leak into the combustion chamber. While it might manifest as burning coolant, it'll often also lead to burning oil.
* Improper Oil Level: While not technically "burning" oil, consistently overfilling the oil can lead to oil being forced into the combustion chamber through the PCV system.
The severity of oil burning varies. A small amount of oil consumption might be acceptable for some older engines, but significant oil burning requires immediate attention to prevent major engine damage. Blue smoke from the exhaust is a common indicator of burning oil. If you notice this, have your car inspected by a mechanic as soon as possible.
