Why does your Nissan Stanza Blow GreyishBlack smoke out of the exhaust pipe?

Sounds to me like gas and or oil smoke. When checking the oil is there a noticable amount gone? If in your area there is a emissions requirement that can tell you a lot about how much actual gas is NOT being burned inside the engine. I would look at major tune up, oil change, and o/2 sensor. Good Luck.

Answer # 2Greyish black smoke is a sign of worn out piston rings

White smoke is a sign of leaky/busted head gasket

Blueish grey smoke is a sign of bad PVC valve, O2 sensor or both