I had exactly the same issue last Friday. I have a 12 plate 2.2 CDTi SE (184ps)
I was just coming to the end of a 60 minute steady drive and as I pulled away from traffic lights I heard a slight "pinking" sound from the engine followed by plumes of white smoke from the exhaust - serious enough to obscure the whole street. Engine didn't cut out but I pulled in and stopped immediately and called the RAC. The roadside verdict was either a Turbo Failure or a failed injector.
Car was taken (on RAC full lift recovery) into local Vauxhall Garage on Monday morning and they did the same - dropped the oil and have found metal fragments in the oil. I'm pretty sure the Turbo is the issue. The problem is that the garage will only look at a complete engine and Turbo replacement at a staggering cost of approx £8k for the short engine plus the cost of the Turbo and labour and ancillaries. Now obviously is time to think how much a 12 plate Antara is worth with 79k on the clock. It is immaculate and has a full VX Service history to date and we are really fond of the car, so don't really want to change it just yet but I cant justify spending £10k on repairing it.
I'm not naming the Vauxhall Dealership as yet as I have asked for the MD to ring me to explain why they cant look at what damage has been done to the engine and price up any engine building work locally. I'm of the opinion that minimal engine damage will have occurred but I feel they are taking the easy way out - either that or they don't want to take the job on. Most of these main dealers only seem to be able to replace parts nowadays, rather than actually repair them.
I'd be really interested to hear how you get on. I will keep you posted as to what happens with my tales of woe too!
Needless to say, if this doesn't get sorted, the Antara will be replaced with something less costly to repair.....like a Range Rover! :-o
Antara 184 SE AWD Manual in Carbon Black