Car engines require a lot of parts working in unison to properly function. There are thousands of explosions happening every minute when your car's engine is running, hence the name "internal ...

The positive crankcase ventilation valve releases exhaust gas and unburned fuel from the engine block into the intake manifold. All engines allow some exhaust gases, unburned fuel and oil to “blow by” ...

The first port of call after your mechanic diagnosed the problem should have been to a Volvo dealer to have them inspect and diagnose the problem. That way they could experience the problem first hand ...