Smoke is coming out of the exhaust pipe. And spells like oil or gas.

What color is the smoke depending on the smoke it could be a head gasket or valve seals or rings. Check the oil level and the coolant level and see if they are low also look at the dip stick and see if the oil on it is milky. Also if smoke smells like fuel vehicle can be running to rich does vehicle run rough and if so check plugs to see if fouled out.I would start with this but you need to see what kind of smoke.

Thank you
Two Lane