As my tame mechanic seems to be on holiday, I'll ask the collected wisdom here.
Vx Omega 2.0 16v ecotec. Starts & runs fine, but as soon as it gets warm it smokes - seriously. It's blue oil smoke, and even at idle there's a visible stream of it from the exhaust - rev it and there's clouds. Leave it idling for several minutes and there's an oily smoky haze round the car. But it doesn't smoke at all from cold.
It's spitting water from the exhaust too, which looks like head gasket I suppose, but it this likely to make it smoke that badly? It seems to drive fine, but as it's not MOT'd I can't test that properly; driving it up and down our slip road it seems fine, pulls well and doesn't misfire.
It has just had a new crank sensor and was fault-code read, after putting in the new sensor it had no fault codes. It was however smoking then. Before that I don't know; it was a second-hand engine which was supposedly running fine before.