Hi there. My lovely 2003 320CD coupe that my dad bought from new and that I now drive, started making embarrassing amounts of black smoke on the (few) times I put it under hard acceleration. My local car part shop suggested I pour a bottle of diesel cleaner into the tank, which I did. The engine now feels as sweet as anything and mpg has risen from 53m/gal to 57.5. - yet the turbo (which was silent before) now makes a subtle 'Wwwooooo' every time I decelerate or change gear. Does anyone know if this a GOOD or a BAD thing? Has the diesel cleaner done damage, or is this a sign all is well with the engine?
