Engine smoking doesn’t necessarily mean that your car is on its last legs, but it certainly does imply that it’s seen better days. Black smoke is almost always the result of oil in the combustion chamber, so the best way to stop smoking is to keep the oil where it belongs. Bear in mind, though, that different colors of smoke mean different things; black smoke indicates oil burning, blue smoke means excess fuel or a malfunctioning ignition system and white smoke is actually steam resulting from a coolant leak in the engine.
Depending on the extent of engine damage, a smoking motor may not be able to be stopped. Try a heavier weight oil to stop an engine from smoking excessively with tips from a certified master mechanic in this free video on car maintenance.