Should the Audi Q5 use 92 or 95 octane gasoline?
2 Answers
According to the official vehicle manual recommendation, the Audi Q5 should use 95 octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, the Audi Q5 can also find this information on the fuel tank cap, which will be clearly marked. Generally, 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 gasoline grade, as high compression ratio engines can also be tuned to use lower octane gasoline. This is 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 the Audi Q5 occasionally uses the wrong gasoline grade, simply switch back to the correct grade after the current tank is used up. However, prolonged 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 change 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 recommended to use higher octane gasoline, using lower octane gasoline can cause engine knocking. Because the octane value is too low, the lowered ignition point may cause premature ignition during the compression stroke. If the fuel ignites before the spark plug fires, resistance will occur during the upward stroke. This resistance makes the engine run very unstably. If the knocking is imperceptible, it only increases noise without significant engine damage. 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.
As an experienced Audi driver who has owned several models, I always stick to 95-octane fuel for my Q5. This 2.0T engine has a high compression ratio, and the manufacturer's manual clearly specifies a minimum requirement of 95-octane gasoline. While 92-octane fuel is cheaper, its lower octane rating can easily cause knocking, and over time, it can affect the piston rings and valves. Once on a long trip, I had to use 92-octane fuel at a remote gas station, and I clearly noticed a knocking sound during acceleration, along with fuel consumption that was over 1 liter higher than usual. If saving on fuel costs is a priority, considering a hybrid model might be a better option. But forcing a premium car to run on lower-grade fuel could end up costing more in engine repairs than five years' worth of 95-octane fuel.
