Should the Audi A4 use 92 or 95 octane gasoline?
2 Answers
Audi A4 requires 95 octane gasoline and cannot use 92 octane gasoline. More details are as follows. Criteria for selecting gasoline: The standard for choosing gasoline is determined by the engine's compression ratio. Using low-octane gasoline in a high-compression-ratio engine will cause a sharp rise in cylinder temperature, incomplete combustion of gasoline, resulting in reduced power output and damage to engine components. For a compression ratio between 7.5 and 8.5, use 92 octane gasoline; for a compression ratio between 8.5 and 9.5, use 95 octane gasoline. Consequences of using the wrong low-octane gasoline: The Audi A4 has a relatively high compression ratio. If low-octane gasoline is used, engine knocking may occur. This is because low-octane gasoline has poorer anti-knock properties compared to high-octane gasoline. Knocking happens when the air-fuel mixture in the combustion chamber ignites, but the flame does not spread completely. The unburned fuel-air mixture at the end of the combustion chamber may self-ignite due to high temperature or pressure during compression. The collision between this flame and the normally ignited flame creates extreme pressure, causing abnormal knocking sounds in the engine.
I remember during the first year of driving my Audi A4, I tried using 92-octane gasoline to save money, only to hear knocking sounds at high RPMs. Later I learned the A4 has a high-compression ratio engine that requires 95-octane fuel. The lower octane rating of 92 fuel makes it prone to knocking, which not only creates noise but can damage internal engine components – long-term use leads to higher repair costs. A friend had similar issues; switching to 95 resulted in smoother power delivery and slightly better fuel economy. The manual clearly states 95-octane or higher is recommended. I advise choosing reputable gas stations as fuel quality varies by region – don't penny-pinch only to pay more later. Additionally, the A4's turbocharged design performs poorly with low-octane fuel. I've made it a habit to always use 95-octane to ensure optimal engine health.
