Initial oil analysis results are revealing TDI's doing very well on dino 15W-40's and 10K mile intervals. In a few years we will know whether longer term use of dino is healthy for the TDI. Until then it's speculation. My bet is you will see very little differnce between dino and syn over the recommended interval.
Thank you to those who are rebeling against the "synthetic oil only" warlords. More results to come this fall.