2001 Nissan Maxima Repair Question
Asked on July 28, 2011
Gas mileage
Will regular gas lessen the gas mileage of a car that requires mid-grade or higher?
Answer
Replied on July 28, 2011
Possibly. Higher octane fuel does not produce more power or fuel mileage. It allows engines to be TUNED for more power. That usually means a higher compression ratio which can result in spark knock. Higher octane fuel is harder to ignite so spark knock is reduced. A lower octane fuel might cause spark knock which will be detected by a knock sensor, (if your engine uses one). The Engine Computer will respond by retarding ignition timing which reduces power and fuel mileage.
Using a higher octane fuel in an engine that is designed for 87 octane will not gain anything by way of power or fuel mileage.