Can 95 and 98 Octane Gasoline Be Mixed?
2 Answers
92 octane gasoline and 95 octane gasoline cannot be mixed because their isooctane content differs. 92 octane gasoline is suitable for engines with low compression ratios, while 95 octane gasoline is suitable for engines with high compression ratios. If 92 octane gasoline is added to a car that requires 95 octane, abnormal combustion may occur, leading to knocking. Knocking not only damages the combustion chamber but also directly affects the normal operation of the engine, potentially causing severe engine damage. Conversely, adding 95 octane gasoline to a car that requires 92 octane will not harm the engine, but since 95 octane is more expensive, it would result in unnecessary costs. Differences between 92, 95, and 98 octane gasoline: Standard gasoline consists of isooctane and n-heptane. Isooctane has good anti-knock properties, with an octane rating of 100, while n-heptane has poor anti-knock properties and is prone to knocking in gasoline engines, with an octane rating of 0. If gasoline is labeled 92 octane, it means the gasoline has the same anti-knock properties as a standard fuel containing 92% isooctane and 8% n-heptane. The same principle applies to 95 and 98 octane gasoline. What to do if the wrong gasoline is added: If gasoline with a higher octane rating than required is added (e.g., adding 95 octane when 92 octane is specified), simply use up the fuel and refill with the correct 92 octane gasoline afterward. If gasoline with a lower octane rating than required is added (e.g., adding 92 octane when 95 octane is specified), you can add a high anti-knock fuel additive. Alternatively, you can drain the fuel tank and refill with the correct 95 octane gasoline. To determine the appropriate gasoline for your car, refer to the vehicle's user manual or check the fuel grade indicated on the fuel filler cap.
I've driven quite a few cars and found that occasionally mixing 95 and 98 octane gasoline once won't cause immediate major issues under normal circumstances, but don't make it a regular practice. 95 octane gasoline has a slightly lower octane rating and weaker anti-knock performance; while 98 octane offers higher knock resistance, making it more suitable for high-performance engines. If mixed, the overall octane rating gets diluted, potentially leading to incomplete combustion, slightly reduced power, or a small increase in fuel consumption. I remember my old car's manual emphasized using 92 or 95 octane, and switching to 98 was fine, but frequent mixing could lead to carbon buildup in the engine over time. It's recommended to check the owner's manual for the recommended fuel type and follow it for optimal performance, especially during long trips when you shouldn't be lazy about mixing. Filling up the tank regularly can save you a lot of hassle. If you must mix, try to do so only in emergencies, then use the original octane rating to empty the tank afterward, keeping the engine running clean.
