What do the smudges mean? (BMW 3 Series E46)

Stains on the garage floor, moisture under the hood or under the car are clear indications of a leak, the source of which must be reported and fixed. Sometimes this source is difficult to determine, especially if the engine has not been washed for a long time. The leak trace may be distorted by the air flow under the car, creating an incorrect idea of the location of the leak.

Warning: Most automotive oils and fluids are poisonous. If they come into contact with your skin, wash them off immediately, and if they come into contact with your clothes, change your clothes.

Haynes advises: The smell of the leak can give you a clue as to what is leaking. Some fluids have a specific color. It can be helpful to wash the car thoroughly and place a clean sheet of paper underneath it overnight to help you locate the leak. Keep in mind that some leaks may only occur when the engine is running.