I'm planning on only using standard Esso when possible. I've always used tesco etc in the past, but wanted to be kinder to the GTD. Plus you get tesco points at Esso now, and it's actually slightly cheaper for me locally!
From the limited research I did (and it's amazing how little info there is out there), the diesel's are from the same source at the depot but Esso/Shell etc, do add additives that are not added to the supermarket lorries.
Anyone know for sure?