How Much 92 Gasoline Should Remain Before Switching to 95?
4 Answers
To extend the engine's service life, it is recommended to switch to 95 gasoline after the 92 gasoline is completely used up. The relevant details about 92 and 95 gasoline are as follows: 1. Short-term mixing is acceptable: Theoretically, mixing different grades of gasoline for a short period will not cause significant harm to the car. However, since the stability of 92 and 95 gasoline differs, extensive mixing may lead to stability issues. Long-term mixing of different gasoline grades can affect the lifespan of the car's ignition system, fuel injectors, and spark plugs. 95 gasoline produces less knocking than 92 gasoline, making the engine quieter. However, since the compression ratio of engines designed for 92 gasoline is not high enough to fully utilize the characteristics of 95 gasoline, incomplete compression and combustion may occur, leading to sluggish acceleration during driving. 2. Which one is suitable: Some vehicles only require 92 gasoline, but their engines were calibrated during the development phase for 95 or higher-grade gasoline. Therefore, when using 95 gasoline, the characteristics of 95 gasoline can be fully utilized to unlock its potential.
Last time I drove my friend's car, I encountered a similar issue. His car usually runs on 92 octane, but this time he wanted to try 95. I asked the mechanic, and actually mixing 92 and 95 is fine—it mainly depends on how much fuel is left in the tank. If the tank is almost empty and the low fuel warning light on the dashboard is on, there’s roughly only 5 to 7 liters left, so you can just fill up with 95 directly. But if there’s still half a tank, the mixed octane rating might not be exactly 92 or 95. It won’t harm the car, but the power response might not be as good as with pure 95. So, every time I switch octane ratings, I wait until there’s about a quarter tank left. That way, after running through half a tank, I can fill up with a full tank of 95, making the transition smooth. Long-term use of higher-octane fuel does help reduce engine knocking, especially in turbocharged cars.
My car has already run 100,000 kilometers, and I've changed the fuel grade three times during this period. There's really no need to overthink the remaining amount when switching from 92 to 95. Even if there are 30 liters of 92 left in the tank, you can just fill it up with 95 directly, and the engine will still run smoothly. As for my personal habit, I prefer to switch when there's about 15% fuel left in the tank. It's most cost-effective to add 95 when the fuel gauge needle just enters the red zone on the dashboard. This way, there's less 92 mixed in, and the proportion of 95 is higher, making the driving experience noticeably better. Honestly, the basic formulations of these two gasoline types are quite similar, with the main difference being the content of anti-knock agents. The engine will automatically adjust the ignition timing to adapt, and mixing them definitely won't harm the car. However, for older cars, engines with a lot of carbon deposits might feel louder when switching to higher-grade gasoline.
Switching gasoline grades isn't as complicated as you think. You can directly add 95-octane fuel no matter how much 92-octane remains in the tank - I've tried filling half a tank of 92 with 95 and drove without issues. But the optimal time is when the fuel warning light comes on, leaving about 8 liters, so the new gasoline concentration exceeds 90% for near-pure 95 performance. Mixed fuel's octane rating is calculated proportionally, and the engine ECU automatically adjusts combustion parameters. Long-term use of higher octane fuel slightly improves power response, especially noticeable when climbing hills. The only thing to note is minor fuel consumption fluctuation during the first tank after switching, which stabilizes after two full tanks.
