Blue smoke can be caused by the injector spray hitting the piston crown, because of poor spray pattern or insufficient compression. A proper compression test costs money but you could put the car into 5th gear and push it along to get some feel if one cylinder has less compression than the others. Injector spray patterns should be tested about 80K miles unless the exhaust is perfectly clean and without nasty smells. That might cost a lot of money on the PD engine so fuel cleanliness is imperative. Fuel smoke has an acrid smell of partly decomposed fuel (and is quite different to oil smoke), and will dilute and contaminate the engine oil causing premature wear, so it needs to be fixed eventually. Are you due for a cambelt change anyway?
So don't use the car unneccessarily for just going round to the shops, the condensation will kill your machinery; don't leave it on idle to warm up, just drive gently until the needles are up on the Temp gauge. Do not shut down immediately after using high power (Motorway) let it cool for a minuite or three at 30mph to let the heat soak away from the red hot Turbo, which would otherwise fry the oil seals and coke up the oil. Think about the thermal stresses. Think about flooring it for a minute or so in top gear to blow the soot off the turbo and the exhaust valves, but take care there are no speed traps around. These engines are built for hard work and I think the PD is one of the finest in service today, but unfortunately I only have the earlier version. = supersparks +