Can 92 and 95 Octane Gasoline Be Mixed Together?

[StJocelyn]

92 octane and 95 octane gasoline should not be mixed. If you accidentally fill up with the wrong gasoline grade occasionally, simply switch back to the correct grade after using it up. However, prolonged use of the wrong gasoline grade can have the following effects: For vehicles designed for lower octane fuel, accidentally using higher octane gasoline will not cause damage. However, the increase in octane rating will alter the fuel's ignition point, leading to delayed combustion in the engine. This results in reduced engine power output and thermal efficiency, with the actual driving experience being poorer performance; For vehicles designed for higher octane fuel, using lower octane gasoline can cause engine knocking. Because the octane rating is significantly lower, the reduced ignition point causes premature ignition during the compression stroke. If the fuel combusts before the spark plug fires, resistance occurs during the upward stroke. This resistance makes the engine run very unevenly. If the knocking is imperceptible, it may only increase noise without obvious engine damage. However, noticeable knocking indicates severe engine conditions, where vibrations not only affect driving stability but also cause abnormal wear on pistons and cylinders, potentially leading to cylinder scoring in severe cases. Besides checking the recommended gasoline grade in the vehicle's manual, you can also find it labeled on the fuel filler cap. Typically, the gasoline grade can also be determined by the engine's compression ratio. Vehicles with compression ratios between 8.6-9.9 should use 92 octane gasoline, while those between 10.0-11.5 should use 95 octane. Higher compression ratios may require 98 octane. However, with modern technologies, the compression ratio alone cannot determine the required gasoline grade, as high-compression engines can be tuned to use lower octane fuel. Other factors, such as ignition timing, turbocharging technology, and Atkinson cycle technology, also play a role. Generally, higher octane gasoline has a higher octane rating and better anti-knock properties. 92 octane gasoline contains 92% isooctane and 8% n-heptane, while 95 octane gasoline contains 95% isooctane and 5% n-heptane.