Shell USA sent me this PDF link
http://s03.static-shell.com/content/dam/shell/static/usa/downloads/fuels/biodiesel-brochure.pdf
They only blend up to B5 so that's safe to use, confirmed by calling all the Shell
Stations in my area near Round lake and Waukegan.
Thanks for this post now you added to my list;
Murphy- Fountain Square Waukegan - D2
Earnies- Lincolnshire-D2
Marathon- Antioch- D2
Phillips 66- Volo -D2
Shell Stations - B5 VW safe
I live in Lake Villa and work in Northbrook so hope this helps. Loving my TDI Jetta 2013, called VW and they gave me the same argument of checking my oil regularly if Bio is used. Will only use minimally in an emergency.