How long will it take to burn spilled oil out of a lawn mower engine?

my son has been turning our lawnmower over frequently to clean the grass out and it is now burning blue smoke i think this means the oil has spilled into the engine we replaced the air filter but not the spark plug since it still starts it hasn't helped so far it runs for a minute then stops all the while burning blue any suggestions?How long will it take to burn spilled oil out of a lawn mower engine?
If this is a 4-stroke engine, any oil that has infiltrated into the cylinders via the pushrod tubes and an open valve (from being turned over) will burn off in a very few moments.





You could have worn rings - that will give continuous blue smoke. How old is the unit? And how often have you changed the oil? Worn rings will also reduce compression - which, together with a partially fouled spark-plug may lead to exactly the symptoms you describe.





Suggestion (and this is somewhat grasping at straws): Purchase one small can of ';Marvel Mystery Oil'; (red can) and a new spark-plug of the correct type, and sufficient small-engine oil to change the existing oil.





Change the oil.


Remove the old spark plug.


Add about 1/8 cup (1 fluid ounce) of Marvel through the spark-plug hole. Add about the same to the engine oil.





With the spark-plug OUT, pull the starting cord a dozen times. This will rinse out the cylinder and perhaps help to clear sludge out of the rings and maybe re-seat them some. Caution: Oil will spray out of the spark-plug hole, so be prepared.





Install the new plug and fresh gasoline.





Start it and run it - see if the blue smoke does not reduce somewhat. If it does, you are exceedingly lucky. On first-start after this treatment, all kinds of blue and grey smoke will come out - this is normal for a minute or so.





NOTE: It is quite unlikely that the turning over of the unit has anything to do with the continuous blue smoke unless it is very low on oil to begin with.





Good luck with it.