can it really have blown 4 turbos ?

do you do a lot of town/stop start driving,know of some vauxhalls with particulate filters on and some of these ran cold all the time as a result the sump filled up with oil/diesel and eventually had so much in the system that the engine started running on this mix and blowing the engine to bits,some had the oil level up to the rocker box,not sure about yours but you may need to get your filter `regenerated`and refill your eyolis tank at the rear wheel and would do no harm to give the motor a good blast now and again,as for your local dealer they should know about this on your motor,not to say that this is your problem but there are lots of posts on this site regarding particulate filters

cdc
February 2011