Originally Posted by cruisin5268d
Best chance to extend the life of the engine? My recommendation would be to purchase the recommended octane.
Purchasing 93 to 87 octane is recommended.
As far as what to avoid in a 2014 Mustang according to Ford, do not use:
• Fuels containing more than 15% ethanol or E-85 fuel.
• Fuels containing methanol.
• Fuels containing metallic based additives, including manganese-based compounds.
• Fuels containing the octane booster additive, methylcyclopentadienyl manganese tricarbonyl (MMT).
From Page 157 of the 2014 Mustang Owner's Manual (3rd Edition) for the 5.0L V8 engine - "Regular unleaded gasoline with a pump (R+M)/2 octane rating of 87 is recommended. Some stations offer fuels posted as “Regular” with an octane rating below 87, particularly in high altitude areas. Fuels with octane levels below 87 are not recommended. Do not use fuels with octane posted on pump below 87. Premium fuel will provide improved performance."
My recommendation to extend the life of the engine, although off topic, would be to run your engine oil about 30 degrees cooler. The cheaper of two Ford made oil coolers is about $139, fits the recent Boss and 11-14 GT's. And is, did you know, standard on all '15 GT's. Can be easily bought from Ford or places like American Muscle.