On our most recent trip we stopped at our nearest Safeway station and found they had switched to B20. Staff, and I, were reluctant to fill because our 2017 MBS has a label for B5 only.
We found several stations on our trip from central Oregon to Half Moon Bay, including Arco, that only had B20 so we made more stops searching for straight up low sulfur diesel than usual for this route.
I hope we can get more guidance, ie mixing half a tank of low sulfur with B20 makes it B10 or B20 is ok with more frequent oil changes.
'17 Forester 2401WS