* Worn Piston Rings: This is a very common culprit. Over time, piston rings wear down, losing their ability to create a proper seal between the piston and the cylinder wall. This allows combustion gases to blow past the rings and into the crankcase, pressurizing the crankcase and pushing oil past the rings and into the combustion chamber where it's burned.
* Worn Valve Stem Seals: These seals prevent oil from leaking down the valve stems. As they age and harden, they become less effective, leading to oil consumption.
* Worn Cylinder Walls: Scratches or excessive wear on the cylinder walls can also contribute to oil burning, similar to worn piston rings. This is often a consequence of low oil levels or using the wrong oil viscosity.
* PCV (Positive Crankcase Ventilation) System Issues: A malfunctioning PCV system can lead to excessive crankcase pressure, forcing oil past seals and into the combustion chamber. A clogged PCV valve is a common cause.
* Leaking Valve Cover Gasket: While not directly burning oil in the combustion chamber, a leaking valve cover gasket can allow oil to leak out, reducing oil levels and potentially leading to related issues down the line if it goes unnoticed.
* Head Gasket Failure: A blown head gasket can allow coolant to mix with oil, leading to milky oil and potentially oil consumption. While not directly "burning" oil, this situation requires immediate attention.
* Improper Oil Level/Viscosity: Using the wrong oil grade (too thin) or simply running low on oil can accelerate wear and tear, leading to oil consumption.
It's important to note that diagnosing the exact cause requires a professional mechanic to inspect the engine. Simply adding more oil is only a temporary fix, and ignoring the problem will likely lead to more serious (and costly) engine damage.
