Smoke coming from the exhaust after a vehicle has warmed up is attributed to oil burning during the combustion process. A switch to a more stable, synthetic oil would be the way to stop a blue-tinged smoke from emerging from the exhaust. However, if the exhaust is smoking with synthetic oil already in the engine, the problem is most likely not with the oil. A trick to diagnosing the problem is to look at the colour of the smoke. It will likely lead to the area of the engine causing the smoke.
Locate the exhaust gas recirculation (EGR) valve near the intake manifold. The valve may be clogged with soot and will need to be cleaned or replaced should your vehicle's exhaust be emitting black smoke.
Spray everything around the EGR valve with a penetrating lubricant.
Disconnect the vacuum line from the EGR valve.
Remove the water line to the driver's side of the valve location. Allow the water from the line to drain into a bucket.
Remove the bolts from the EGR valve.
Remove the fitting on the exhaust manifold.
Follow the exhaust tube from the EGR valve to the intake plenum and disconnect it. Remove the EGR valve.
Clean the EGR valve by soaking it in gasoline. If it does not come clean, the valve will need to be replaced.
Reconnect the EGR valve after cleaning or replacement.
Investigate the cylinder head and head gasket for leaks. White smoke is a telltale sign water is leaking into the engine.
Locate the coolant reserve container or, if there is no reserve, the radiator. Remove the cap only when the engine is cool.
Pour a block sealer into the coolant reservoir.
Replace the cap and turn on the vehicle. The sealer will be sucked into the crack causing the leak. The crack will be filled with the sealer, a sodium silicate also called water glass.
Remove the gas cap.
Insert a hose into the fuel tank. Siphon the fuel out of the fuel tank. Something may have been added or got into the fuel tank.
Fill the tank with fresh fuel.
Replace the gas cap.