The fuel regulations require that all fuel pumps be labeled to inform the user which fuel they are dispensing into their vehicle. These labels will state which engines/vehicles that the specific fuel is suitable for use in. There will also be labels on the 2007 engines, per § 86.007-35, stating which fuel should be used.
Question and Answer was originally posted at Questions and Answers on the Clean Diesel Fuel Rules (PDF)(135 pp, 888 K, EPA420-B-06-010, July 2006, About PDF)