Look, the number of turbos on Australian roads is massive.
Many of the diesel engines have called for simple 15W40 diesel specs, A3/B4 or C3...Dexos 2 is more recent (including in the gassers, as I've previously explained). Ford, on their high performance turbo 6, also called for 15W40 SL...a grade scarcelely likely to be syntetic, and certainly not called for being a synthetic in the manual.
There are literally millions of turbos in the country, and most of them not running any type of synthetic.
If your claims were true, there would be a pile of failed turbos at every street corner, and that's simply not the Australian experience.
Unless you've got links to photos of these piles, I'll have to suggest that you are looking at the issue through the eye's of a convert to tricky advertising, rather than rationally evaluating the evidence.