2. Damaged valve guide seals. Valve guide seals are supposed to prevent oil from seeping into the valve guides from the cylinder head. When valve guide seals become damaged, oil can leak past them and into the combustion chamber, where it is burned and exits the tailpipe as blue or white smoke.
3. Blown head gasket. A blown head gasket can allow coolant and oil to mix, which can then cause the oil to exit the tailpipe as white or gray smoke.
4. Turbocharger failure. A turbocharger can fail due to a number of reasons, but one of the most common reasons is oil starvation. When a turbocharger fails due to oil starvation, it can cause the oil to back up into the exhaust system and exit the tailpipe as blue or white smoke.
5. Defective PCV (positive crankcase ventilation) valve. The PCV valve is supposed to regulate the flow of gases and oil vapor from the crankcase to the intake manifold. When the PCV valve fails, it can cause excessive amounts of oil vapor to enter the intake manifold, which can then be burned and exit the tailpipe as blue or white smoke.
6. Oil overfill. If you overfill your engine with oil, it can put pressure on the engine seals and cause them to leak. This oil leakage can then cause the oil to enter the combustion chamber and exit the tailpipe as blue or white smoke.
