Can 92 Gasoline Be Used in a Car That Requires 95?

[McRuby]

A vehicle that requires 95-octane gasoline should not use 92-octane gasoline. If the wrong gasoline grade is accidentally used occasionally, simply switch back to the correct grade after consumption. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles designed for lower-octane gasoline, using a higher grade will not cause damage, but the increase in octane rating may 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 experience being poorer performance. For vehicles designed for higher-octane gasoline, using a lower grade can cause engine knocking. This occurs because the significantly lower octane rating reduces the fuel's ignition point, causing premature ignition during the compression stroke. If combustion happens before the spark plug fires, resistance is created during the upward stroke, making the engine run very unstably. Mild knocking may only increase noise without significant engine damage, but noticeable knocking indicates severe engine conditions, affecting driving stability and causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring. Besides checking the owner's manual for the appropriate gasoline grade, you can also find this information on the fuel filler cap. Typically, the gasoline grade can be determined by the engine's compression ratio: vehicles with a compression ratio between 8.6-9.9 should use 92-octane gasoline, while those with a ratio between 10.0-11.5 should use 95-octane. However, with modern technologies, the compression ratio alone is no longer the sole determinant. High-compression engines can be tuned to use lower-octane gasoline due to other factors like ignition timing, turbocharging technology, and Atkinson cycle technology. 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.