Can 92 and 95 Gasoline Be Mixed?
2 Answers
92 and 95 gasoline cannot be mixed because they have different isooctane contents. 92 gasoline is suitable for engines with low compression ratios, while 95 gasoline is suitable for engines with high compression ratios. If 92 gasoline is added to a car that originally requires 95 gasoline, abnormal combustion may occur, leading to knocking. Knocking not only damages the combustion chamber but also directly affects the normal operation of the engine, and in severe cases, it may cause engine damage. If 95 gasoline is added to a car that originally requires 92 gasoline, although it won’t damage the engine, 95 gasoline is more expensive than 92, resulting in unnecessary costs. The differences between 92, 95, and 98 gasoline: Standard gasoline is composed of isooctane and n-heptane. Isooctane has good anti-knock properties, and its octane number is defined as 100; n-heptane has poor anti-knock properties and is prone to knocking in gasoline engines, so its octane number is defined as 0. If the gasoline is labeled as 92, it means the gasoline has the same anti-knock properties as standard gasoline containing 92% isooctane and 8% n-heptane. The same principle applies to 95 and 98 gasoline. How to handle adding the wrong gasoline: If the gasoline added has a higher octane rating than required by the car (e.g., 95 instead of 92), simply use up the gasoline and then refill with 92. If the gasoline added has a lower octane rating than required by the car (e.g., 92 instead of 95), you can add a high anti-knock fuel additive. Alternatively, you can drain the fuel tank and refill with 95 gasoline. To determine the correct gasoline for your car, refer to the vehicle’s user manual or check the fuel rating marked on the fuel tank cap.
Once when I was driving out of town and my fuel tank was nearly empty, the only gas available at the service station was 92 octane, while my car normally uses 95. So I filled half with 92. After driving a few hundred kilometers, the engine started to shake slightly, and the noise increased during acceleration. Later, the mechanic at the repair shop explained that mixing 92 and 95 octane gasoline can lead to incomplete combustion, forcing the engine control system to constantly adjust the ignition timing. While it might not cause immediate issues, long-term use increases the risk of carbon buildup and can even lead to piston damage due to knocking. So, I recommend not mixing fuels to save a little money—always stick to the octane rating recommended in your car's manual. If you have no choice but to mix, refill with the correct fuel as soon as possible to flush the tank. For daily use, 95 octane, with its higher anti-knock index, is better suited for high-load urban commuting engines, offering better protection.
