Got shot of our Focus at about the 70K mark, the injector oil seals on No.3 were leaking which is the beginning of the start of “black death”.
The engine combustion gases end up leaking into the oil which clogs up the oil ways leading to turbo failure.
The Ford technical bulletin for this fault involves taking sump off and cleaning it, replacing all the turbo pipe work and cleaning the oil pick ups as well as flushing the engine repeatedly with clean oil and measuring the flow rate to the turbo.
Failure to get this right results in turbo’s going pop every few thousand miles.
Plenty of info here:
Ford Turbo problems