Can 92 and 95 gasoline be mixed when refueling a car?

[DiElliana]

92 gasoline and 95 gasoline cannot be mixed because their isooctane content is different. 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 should use 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 should use 92 gasoline, although it will not damage the engine, 95 gasoline is more expensive than 92 gasoline, resulting in unnecessary costs. 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 that 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 is of a higher octane rating than the car requires, for example, adding 95 gasoline when 92 is specified, you can simply switch back to 92 gasoline after consuming the current fuel. If the gasoline added is of a lower octane rating than the car requires, for example, adding 92 gasoline when 95 is specified, you can add a high anti-knock fuel additive. Alternatively, you can drain the fuel and refill with 95 gasoline. To find out which gasoline your car requires, you can refer to the car's user manual or check the fuel rating marked on the fuel tank cap.

[DiGabrielle]

I previously worked in the automotive engineering field, and mixing 92 and 95 gasoline is a common confusion. Simply put, it's caused by the difference in octane ratings. 92 has a lower octane rating, suitable for low-compression engines, while 95 is higher, designed for high-performance engines. When mixed, the octane rating averages out. If your car is specified for 95, mixing with 92 may cause knocking—that is, too rapid combustion, impacting pistons or cylinder walls, leading to long-term damage to the engine core and increased repair costs. Occasionally using it in an emergency is fine, as modern ECUs can fine-tune, but don’t make it a habit, especially for turbocharged models, which face higher risks. Additionally, different grades have varying additive compositions, and mixing may reduce anti-carbon buildup effectiveness. It’s best to always follow the user manual’s recommended grade to protect the engine and extend its lifespan—this is the safest and most cost-effective choice.

[JustinRose]

I usually fill my car with 95-octane gasoline. Once on the highway, the service station only had 92-octane, so I had no choice but to mix them. I felt a slight decrease in power, and the engine noise was louder during acceleration, but fortunately, there were no malfunctions. A friend at the repair shop told me that most cars can handle occasional mixed fueling without issues because the sensors automatically adjust the ignition timing to prevent serious problems. However, frequent mixing can lead to carbon buildup or knocking, especially under high load, which may damage components. From a fuel-saving perspective, while mixing with 92-octane is cheaper, the increased fuel consumption might offset the savings. If you frequently drive long distances, it's best to plan your refueling stops in advance and stick to the specified octane rating. In case of an emergency mix, drive gently and switch back to your regular fuel next time.

[OBrynlee]

Don't mix 92 and 95 gasoline - it's no trivial matter. The significant octane difference may cause knocking or incomplete combustion, putting stress on the engine. I've seen a car with severely worn piston rings after years of mixed fueling. If your manual specifies 92, mixing with 95 has minor effects; but 95-specified cars mixing with 92 risk serious issues. In emergencies, limit mixing to half a tank and revert ASAP. Always follow the manufacturer's recommended grade for optimal performance.

[StJune]

From an automotive safety perspective, blending gasoline of different octane ratings carries potential risks. 92-octane fuel has a lower octane value while 95-octane is higher. The resulting octane reduction from mixing them may cause knocking in high-compression engines, potentially leading to overheating or component damage. I strongly recommend strictly following the manufacturer's recommended octane rating to avoid abnormal engine wear and increased maintenance costs. If accidentally filled with the wrong grade once, drive cautiously until the next refueling to revert to the correct rating. Additionally, mixing fuel additives may yield suboptimal effects and impact emission compliance. Always consult the owner's manual to ensure proper fuel usage for vehicle protection.