Is it okay to mix 92 and 95 gasoline?

[ZoeMarie]

92 gasoline and 95 gasoline should not be mixed. If you accidentally fill up with the wrong gasoline grade, simply switch back to the correct grade after using it up. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles requiring lower-grade gasoline, mistakenly using higher-grade gasoline will not cause damage, but the increase in octane rating will alter the fuel's ignition point, leading to delayed combustion in the engine. This means both the engine's power output and thermal efficiency will decrease, resulting in poorer performance. For vehicles requiring higher-grade gasoline, using lower-grade gasoline can cause engine knocking. Because the octane rating is too low, the gasoline's ignition point decreases, causing it to ignite prematurely during the compression stroke. If combustion occurs before the spark plug fires during the compression stroke, resistance will arise during the upward stroke. This resistance makes the engine run very unstably. If the knocking is imperceptible, it only increases noise and does not significantly damage the engine. However, noticeable knocking indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and in severe cases, cylinder scoring. In addition to checking the appropriate gasoline grade in the car's manual, you can also find it on the fuel tank cap. Usually, the gasoline grade can also be determined based on the engine's compression ratio. Cars with a compression ratio between 8.6-9.9 should use 92 gasoline, those between 10.0-11.5 should use 95 gasoline, and those with higher compression ratios should use 98 gasoline. However, with the use of new technologies, the compression ratio alone cannot determine the gasoline grade. High compression ratio engines can also be tuned to use lower-grade gasoline, as factors like ignition timing, turbocharging technology, and Atkinson cycle technology also play a role. Generally, the higher the gasoline grade, the higher the octane rating and the better the anti-knock performance. 92 gasoline contains 92% isooctane and 8% n-heptane, while 95 gasoline contains 95% isooctane and 5% n-heptane.