Question

1. a vehicle blows blue gray exhaust from its tailpipe only when first started in the morning. the most likely cause of this condition is: worn piston rings. a lean fuel condition. a leaking fuel injector. leaking valve seals.

Explanation:

When valve seals leak, oil can enter the combustion chamber overnight. When the engine is started in the morning, this oil burns, producing blue - gray exhaust. Worn piston rings would cause continuous blue - gray exhaust, not just on startup. A lean fuel condition and leaking fuel injector would not typically cause blue - gray exhaust on startup specifically.

Answer:

Leaking valve seals.