Can an Audi Always Use 92 Octane Gasoline?
2 Answers
According to the official vehicle manual recommendation, Audi should use 95 octane gasoline. It is not advisable to use 92 octane gasoline. In addition to checking the suitable gasoline grade in the vehicle manual, Audi owners can also find this information on the fuel tank cap, which will be clearly marked. Typically, the appropriate 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 some new technologies, the compression ratio alone cannot determine the gasoline grade to be used. A high compression ratio can also be adjusted 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 value 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 occasionally uses 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, using higher octane gasoline will not cause damage, but the increase in octane value 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 in actual driving experience. For vehicles recommended to use higher octane gasoline, using lower octane gasoline can cause engine knocking. Due to the significantly lower octane value, the gasoline's ignition point decreases, causing it to ignite prematurely during the compression stroke. If combustion occurs before the spark plug ignites 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 with no obvious damage to the engine. However, if the knocking is noticeable, it indicates severe engine conditions. The vibration not only affects driving stability but also causes abnormal wear on the pistons and cylinders, and in severe cases, can lead to cylinder scoring.
I've worked in the auto repair industry for over 20 years and seen too many Audi owners try to save a few bucks by using 92-octane fuel, only to end up with constant engine knocking—what we call detonation. Audi's high-compression engines are designed to run on 95 or 98-octane gasoline to prevent pre-ignition. 92-octane fuel has too low of an octane rating, and long-term use leads to carbon buildup, clogged fuel injectors, damaged oxygen sensors, and even engine overhauls. Last year, an A4 owner insisted on using 92-octane, and within six months, the engine warning light stayed on constantly, resulting in repair costs over 10,000 yuan—wiping out any fuel savings. The owner's manual clearly states to use 95-octane or higher—don't cut corners for small savings. For precision-engineered cars like Audis, using the right fuel ensures longevity; otherwise, repairs are expensive and troublesome.
