That means that you need to change the oil filter. Or, it could mean that the combustion of the oil is out of tune, and you need to have a qualified oil burner technician look at it.
The preposition is "up".
needs to be cleaned
chimney must be to smoke
smoke can reverse meaning the smoke( if you are very unlucky) can get in your house . and soms other stuff .
shouldn't your question be," A passage for smoke in a chimney"? just saying
Black smoke issues from the chimney of the Sistine Chapel if a ballot fails to elect a new pope.
the higer pressure at the bottom of the chimney pushes air and smoke up the chimney
There are many causes of air pollution other than chimney smoke. Cars for example are a leading cause of air pollution.
A chimney is a vertical shaft which is usually placed above something which produces a large amount of heat, smoke or steam. Its purpose is to direct the heat, smoke or in a desirable direction which will not cause damage or issues to its path.
"You're too young to smoke!"
A chimney will suck air from the house only if there is wind above the chimney. Air movement at the top causes a partial vacuum in the chimney which pulls the smoke up. The smoke could get into the house due to several reasons: there is no wind above the chimney; the chimney is blocked, the smoke is being directed away from the chimney due to other areas of low pressure in the house. You could probably rectify the problem by raising the chimney so that it catches more wind, cooking closer to the chimney inlet, making chimney diameter wider so that there is less resistance to the passage of smoke. Hassan
It could be steam from the heater core