Does Using 92 Octane Gasoline Affect Audi?

[EllianaRose]

According to the official vehicle manual recommendation, Audi should use 95 octane gasoline, and using 92 octane may have adverse effects. In addition to checking the appropriate gasoline grade in the vehicle manual, Audi owners can also find this information on the fuel tank cap, which is usually marked there. Typically, the gasoline 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 gasoline, while those with a compression ratio between 10.0-11.5 should use 95 octane gasoline. However, with the application of new technologies, the compression ratio alone cannot determine the required gasoline grade. High-compression engines can be tuned to use lower-octane gasoline because, besides the compression ratio, other factors such as ignition timing, turbocharging technology, and Atkinson cycle technology also play a role. Generally, the higher the gasoline octane number, the higher the octane rating and the better the anti-knock performance. 92 octane gasoline contains 92% isooctane and 8% n-heptane, while 95 octane gasoline contains 95% isooctane and 5% n-heptane. If an Audi is occasionally filled with the wrong gasoline grade, simply switching back to the correct grade after consumption is sufficient. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower-octane gasoline, accidentally using higher-octane gasoline will not cause damage, but the increased 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 practical experience being poorer performance. Conversely, using lower-octane gasoline in vehicles recommended for higher-octane fuel can cause engine knocking. Due to the significantly lower octane rating, the gasoline's ignition point decreases, causing premature ignition 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 unstably. If the knocking is imperceptible, it may only increase noise without obvious engine damage. However, noticeable knocking indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring in severe cases.

[SanBradley]

Using 92-octane gasoline in an Audi definitely has negative effects. The manufacturer's requirement for 95-octane or higher fuel isn't arbitrary—the engine's high compression ratio simply can't handle the knocking caused by lower-grade fuel. I know several owners who opted for cheaper 92-octane gas, and they later faced issues like warning lights and engine vibrations; the repair costs far exceeded the small savings on fuel. Components like spark plugs and fuel injectors also become prone to carbon buildup, making the engine feel sluggish even on highways. If you absolutely must use 92-octane in an emergency, remember to burn it off quickly and add a fuel system cleaner afterward, then switch back to 95 or 98-octane next time.