What grade of gasoline should an Audi RS7 use?
2 Answers
Audi RS7 should use 98-octane gasoline, as this is the recommended fuel grade in the vehicle's official user manual. In addition to checking the appropriate gasoline grade in the user manual, you can also find it on the fuel tank cap, which will also indicate the recommended grade. Typically, the fuel 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, those between 10.0-11.5 should use 95-octane gasoline, and if the compression ratio is higher, 98-octane gasoline is recommended. However, with the application of new technologies, the compression ratio alone cannot determine the appropriate gasoline grade, as high-compression engines can also be tuned to use lower-octane fuel. 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 grade, the higher the octane number 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 wrong gasoline grade is occasionally used in an Audi RS7, simply switching back to the correct grade after consumption is sufficient. However, prolonged use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower-octane gasoline, using a higher-octane grade will not cause damage, but the increased octane number can alter the fuel's ignition point, leading to delayed combustion in the engine. This results in reduced engine power and thermal efficiency, with the practical effect being poorer performance. For vehicles recommended to use higher-octane gasoline, using a lower-octane grade can cause engine knocking. Because the octane number is significantly lower, the lowered ignition point may cause the fuel to ignite prematurely during the compression stroke. If detonation occurs before the spark plug fires, resistance will develop during the upward stroke. This resistance makes the engine run very unstably. If the knocking is mild, 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, and in severe cases, cylinder scoring.
When driving a high-performance sedan like the Audi RS7, I always remember its recommendation to use 98-octane gasoline, which allows the engine to deliver maximum horsepower output and avoids issues like shaking or reduced efficiency that might occur with lower-grade fuel in regular cars. The RS7's engine is sensitive to octane levels, and using 98-octane ensures smooth acceleration and robust power, especially when driving at high speeds in Sport mode, where the overall responsiveness feels much more exhilarating. While occasionally using 95-octane might suffice in the short term, prolonged use could increase the risk of carbon buildup and result in higher fuel consumption. I recommend sticking to reputable, high-quality 98-octane fuel for regular refueling—don’t skimp on cost, as maintenance for such a car is expensive, and repairs can be heartbreaking. Regularly checking fuel quality can also extend engine life, and filling up with 98-octane before long trips significantly enhances both the driving experience and safety.
