Ford Mustang Owner's Manual page 336

Scheduled Maintenance Guide
Reset your Intelligent Oil Life Monitor™ after each engine oil and filter
change; refer to the Instrument Cluster chapter (except Shelby
GT500 which does not have this feature).
Exclusive use of E85 (Flex Fuel Vehicles only)
Every oil change interval – If ran exclusively on E85, fill the fuel tank full with
336
2011 05+ Mustang (197)
Owners Guide, 1st Printing
USA (fus)
regular unleaded fuel.