2.0 hdi 90 blueish smoke under acceleration

[jayspug86]

hi I was driving normally yesterday when all of a sudden I noticed some blueish smoke from the exhaust which almost goes if driving gently, however if I take the revs up its blowing out a fairbit of blueish smoke.

iv had the rac out and engine runs sweet as a nut with no over heating,and no smoke from cold start, and no smoke idling.

coolant level is fine and oil level full

any ideas??