strange oil smoke behaviour on cold start

I have a 2005 3.0 TDi which has about 109k miles on the clock. I have had it from new and had very little go wrong - so far, so good.
Just lately on cold start, there has been a puff of blue oil smoke which stops more or less straight away, except if forced to idle while cold then there is a lot of oil smoke when setting off again.
This does not happen once the engine has warmed up and in normal running I am told that there is no apparent oil smoke being produced (by my son when he followed me along a dual carriageway).
It does not seem to be using any oil and it is possible, but I am not certain, that this began to happen after the last service (done by a non-audi garage, who have worked on it for me for the past 12 years without issue).

Can anyone shed light on what might be the cause?
When all is said and done the engine has not done outrageous miles and is still in bog standard state.

Any help would be appreciated

marsmail

B5NUT, thanks for the reply and suggestion.
Knowing very little about diesels, as I do, I don't understand why problems with injectors should cause what seems to be blue oil smoke. Years ago I had a van where the start heater system failed. Crank for what seemed for ever produced a lot of white smoke before it finally fired. Now, hard acceleration produces a bit of black smoke, but blue oil smoke?
Perhaps you could take a moment to advise?

Gaxwould = Gloworms? sorry where do they come in?

marsmail

Well, finally got the scan done - 5 out of 6 are out of range (2 quite badly) so now workshop is getting 6 replacements and will book the car in once they arrive.
Hopefully that will cure the problem for a few more years of motoring!

marsmail

Just a final update - Now has "rebuilt" Bosch injectors fitted and smoke is no more. Also, the engine seems just a little bit smoother running and possibly a little bit more responsive (although that might be my imagination).
I have not done enough miles to know if the fuel consumption has improved.

marsmail