Heavy Smoke On Start Up

Hi, I`m looking for some advice. I have a 110 csw 2.5td and on starting first there is loads of smoke from exhaust , it looks bluish. When i get going it clears but if i go down hill with my foot lifted off throttle smoke bellows out the back again.
I have had family members follow me and on normal driving it`s fine, only slight black smoke on acceleration.
I have put in new injectors,fuel filter and air filter and i`m now at a loss.
CAN SOMEONE SUGGEST WHAT IT MIGHT BE AND HOW TO REDUCE IT OR ILLIMINATE IT.
CHEERS & A MERRY XMAS AND HAPPY NEW YEAR.

I'm no expert, but it sounds like worn valve guides to me. Oil drips down when stopped and gets sucked in when you are on overrun, like going downhill using engine braking. I don't think its a major issue unless you are using a lot of oil in which case I would look at compression - ie pistons and rings etc.

Had it on mine, (white smoke) it was pump timing.(200 TDI) The last owner had the belt changed but the timing wasn't checked as it can be a pain to do.