On the Direct injection thing, it uses similar durations with increased pressure to lift the fuel volume, it's really not true (these days) that atomised fuel ends up condensing on top of the pistons at high power, it won't inject more than it can combust, but there is some that doesn't vapourise and goes out the exhaust as particles.
And I know some of you guys don't like diesels, but direct injection petrol engines are going to end up with particle filters, as they emit almost as many as diesels on the EU emissions run, but at present they don't (yet) have a limit.
So how do we get the fuel in there? Well the main problem isn't at high durations ( though it was years ago with VAG and Mitsi) its at low power, they tend to pre-ignite, i.e before the spark even at maximum advance, this results in incomplete combustion and particles going out the exhaust and yes, oil washed from the bores and fuel in the sump.
Now this is not unknown by engine designers, and the do their best to work around it, there are plenty SAE papers on the subject.
It does not usually cause a problem, but you have a big job for the oil as these engines:
Have fuel dilution
In your case you seem to have a perfect storm, you may indeed also have a leaky injector as the auto lusso man suggests, and that's the tipping point, though the common consensus with DI petrol turbo's is that high quality oil, changed frequently 'should' withstand it.
The turbo obviously has started showing the effects with the noise, and eventually died.
The VAG TFSI used to sludge itself up on this, with similar results.
A bit short, but to the point.