Should I be worried?

I have a 2000 996C2 cab in Dubai where I live at present. A couple of weeks ago after a 100 mile drive at speeds of between 80 - 100mph I parked up for a couple of hours. When I restarted the car there was a plume of smoke - and I mean a plume - from the exhausts. I left the engine idling and the smoke soon cleared, there were no signs of any oil leaks and temps were normal. I drove the car home without any further smoke or problems and left it for a couple of hours and re-started again and no smoke this time and it has been fine since. It doesn't use oil and oil pressure is normal at just over 1 bar at idle when hot and 4 bar at 3000rpm hot. Can anyone explain what might have happened? Is it possible to get an oil surge into the bores - I did take a couple of corners quite quickly just before I stopped. Any ideas and should I get it checked out? Many thanks

What colour was the smoke? White or blue? Plumes of white smoke can often be caused by a failed air/oil separator.

I would have said grey/blue rather than white. Would a failed oil/water seperator would result in oily water in the expansion tank? The strange thing is that it hasn't emitted any smoke since. The oil was changed recently and I will double check that it hasn't been overfilled. Is there a breather anywhere that might have got blocked? If blue smoke what would that indicate in your opinion? One other thing worth mentioning although dont think it is related but I had a heater core issue and that was resolved by bypassing the heater matrix - dont really need a heater here and it is a dash out job. Many thanks

It may be overfilling would cause the smoke after a spirited run, but oily water in the expansion tank doesn't sound good. White smoke is what you get when oil mist from the sump is burnt in the cylinder by a failed air/oil separator. A puff of blue smoke at startup is common, usually caused by a small amount of oil laying on the cylinder liners after a few hours laid up. Plumes of blue at the end of a run is much more unusial. I wouldn't like to guess, to be honest. I would get it checked out by a specialist if you have one over there. The air/oil separator is the breather - there isn't a separate pipe.

The water in the expansion tank is not oily - may have confused you there. I just assumed if the seperator was faulty then I would have oily water. There is absolutely no smoke whatsoever now even if I give it a bit of welly so am confused. I will check the oil level tomorrow to make sure that isn't the problem. The fact that it has only happened once is what seems strange. I dont have a lot of faith in the agents here as whilst they are an official OPC they tend to go for replacement rather than repair and are likely to pull my engine to bits, find nothing wrong then suggest a new engine!! Thanks for your input.

Without oil in your expansion tank, no oil dumping on the ground, no grinding noises, and only having happened once, I would not worry too much.

Sorry, I misunderstood what you meant by oil in the water tank. A failed AOS wouldn't do that. An easy-ish way to tell if it has failed is to undo the inlet hose to the throttle body, open the butterfly, and look inside with a torch. If there is an oily residue on the inside, then it is likely the AOS has failed. If it is dry, then it is OK. As Rod says, if everything he mentions is OK, and the oil isn't overfilled, then put it down to a one-off.