Could do with some advice on this one...
Just had a phone call of a mate with a car as in title. He did a service on it at the weekend including oil and filter change. After filling the oil he checked the dip-stick and realised he had over filled it with oil, although he says "not by much".

He drove it this morning but after about a mile it started making a rattling noise under acceleration. Than it suddenly revved up to the redline by itself even when he disengaged the trottle. He quickly turned the ignition off and it stopped. At this point he could see anything for the thick smoke that had pumped out of the exhaust.
He managed to get the car back home by driving on tick over. Tonight he removed the sump plug to drain some oil out of it. Only about 200ml came out though!

The strange thing is that the dip stick is still showing more than the max level of oil on it!! He even put some more oil in to see if it would come out of the sump hole, but it never came out..
I thought at first the pressure had pushed oil into the turbo causing the redlining and smoke, but surely it wouldn't have burnt it all off that quickly. And why the dip stick level???
It's got me stumped!! I'm going to take a look tomorrow and would appreciate any suggestion on where to start with this...
Cheers
