Subaru's guidance on fuel requirements for the U.S. market 2014 Forester http://techinfo.subaru.com/proxy/71914/pdf/ownerManual/071914_2014_Forester/MSA5M1403BrevSTIS_13.pdf
Non-turbo models
The engine is designed to operate using unleaded gasoline with an octane rating of 87 AKI (90 RON) or higher