Using 91-octane premium fuel instead of 87-octane regular fuel will only increase your engine's power if your car's manufacturer specifically designed the engine to require it.
Higher octane fuel resists knocking or 'pinging' under compression, which is a premature ignition of the fuel-air mixture. Engines designed for higher octane can take advantage of this resistance to operate at higher compression ratios or with more advanced timing, which can lead to increased horsepower and efficiency. However, if your vehicle's owner's manual specifies regular 87-octane fuel, using premium 91-octane will likely offer no discernible performance benefit and is generally not recommended. Always consult your vehicle's manual for the correct fuel grade.
Fuel octane requirements are determined by the vehicle manufacturer and using a higher octane than recommended typically provides no benefit.
Where can I find out what type of gasoline my car needs?
The most reliable place to determine the correct type of gasoline your car needs is your vehicle's owner's manual. It will clearly state whether the manufacturer recommends or requires regular (87 octane), mid-grade (89 octane), or premium (91 or 93 octane) fuel. You can also often find this information on a sticker located inside the fuel filler door or on the gas cap itself. Checking these sources ensures you use the fuel grade that the vehicle was designed for, optimizing performance and preventing potential engine issues.