Starting with the basics, burning oil gives blue smoke, rich running (too much fuel) gives black smoke. A cold engine or cold exhaust will emit white water vapour (steam) which many people mistakenly call white smoke. If the engine sound ok take it for a 5 or 6 mile ride accelerating up to about 7,500 rpm in the gears and keep listening. Return home and have a good long look and listen. Don't rev it that high again in neutral, it's the same effect as trying to pedal a push bike really fast without a chain on, your legs will tell you what the con-rods are going through! Hope all is well, if it ain't broke don't fix it, and carry a mobile phone with your AA/RAC card! Stay Upright, Michael.