Mustang: Should You Use 92 or 95 Octane Fuel?
1 Answers
According to the official vehicle manual recommendation, the Mustang should use 95 octane fuel. In addition to checking the appropriate fuel grade in the vehicle manual, the Mustang owner can also find this information on the fuel tank cap, which is usually labeled. Generally, the fuel grade can also be determined based on the engine's compression ratio. Vehicles with an engine compression ratio between 8.6-9.9 should use 92 octane fuel, while those with a compression ratio between 10.0-11.5 should use 95 octane fuel. However, with the application of new technologies, the compression ratio alone cannot determine the fuel grade—high compression ratios can still be tuned to use lower octane fuel. This is because other factors, such as ignition timing, turbocharging technology, and Atkinson cycle technology, also play a role. Generally, the higher the fuel octane number, the higher the octane value and the better the anti-knock performance. 92 octane fuel contains 92% isooctane and 8% n-heptane, while 95 octane fuel contains 95% isooctane and 5% n-heptane. If the Mustang occasionally uses the wrong fuel grade, simply switch back to the correct grade after consumption. However, long-term use of the wrong fuel grade can have the following effects: For vehicles recommended for low-octane fuel, using higher octane fuel will not cause damage, but the increased octane value alters the fuel's ignition point, leading to delayed combustion in the engine. This reduces both the engine's power output and thermal efficiency, resulting in poorer performance. For vehicles recommended for high-octane fuel, using lower octane fuel can cause engine knocking. Due to the significantly lower octane value, the fuel ignites prematurely during the compression stroke. If combustion occurs before the spark plug fires, resistance is generated during the upward stroke. This resistance makes the engine run very unevenly. If the knocking is mild, it may only increase noise without obvious engine damage. However, severe knocking indicates critical engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and in extreme cases, cylinder scoring.
