i had this problem about 3 years ago and it was the crankcase oil filter changed it and no more smoke but ive just had the same problem again its been smoking for about a month i changed the filter but this time it wasn't the filter. the other day the car started misfiring and clouds of smoke coming out which ive been told is the turbo oil seals or turbo piston ring has let go. going to swap turbo from the missus car later to see if its the turbo ill let you know what happens