What might cause blue smoke to come from a tailpipe?

Blue smoke coming from a vehicle’s tailpipe is primarily indicative of burning oil. This occurs when engine oil seeps into the combustion chamber and is burned along with the fuel. The most common reason for this to happen is linked to an excessive amount of oil entering the engine, which can occur from over-flooding.

When over-flooding occurs, oil may bypass the piston rings or valve seals, leading to its combustion. This situation typically arises due to an excessively rich fuel mixture, often caused by malfunctions in the fuel delivery system that can allow too much fuel and oil into the combustion chamber. As a result, the visible blue smoke is a clear sign of oil burning, which points directly to the effect of over-flooding.

Other options may relate to different engine issues, but they do not primarily result in blue smoke. A low oil level typically leads to increased engine wear or failure rather than the specific symptom of blue smoke. A malfunctioning exhaust system may produce different types of smoke or exhaust issues, while a blocked air filter generally causes a reduction in performance and may result in black or gray smoke rather than blue. Understanding the characteristic signs of engine problems helps in diagnosing and resolving issues effectively.