Whenever the engine has been running for a while and then I turn it off and then start it again after 5-10 minutes it puffs out white smoke for about a minute. I know this is evidence of o-ring failure but could it be anything else? I took it to a mechanic and he said it could be a snap ring or something in the turbo.

He was the one that sold it to me and it is still under warranty so I dont think he would like to admit it being an o-ring.

It used to do this and then it stopped for a while. I have just changed the oil and now it seems to have started again.

Any ideas???