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Q: Excessive blue smoke

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Car failed test on emissions last week. Was told the cat is gone for a new 1 fitted today and about an hour later car started smoking thigh blue smoke.. car is well serviced and maintained.. never blew smoke before.. I put in an oil additive and ran it for 2 hours with no change.. any suggestions

My car has 99500 miles.
My car has a manual transmission.

A: Blue smoke coming from the exhaust generall...

Blue smoke coming from the exhaust generally means that the motor is burning the engine oil. This can happen for a couple of different reasons such as worn piston rings or leaking valve guide seals. When this happens, the engine oil is burned in the combustion chamber along with the fuel which is what generates the blue smoke coming from the exhaust. I would recommend having an expert from YourMechanic come to your location to inspect your car's running condition to determine what may be causing the blue smoke coming from your exhaust.

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