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.
Greyish 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