What to Do If 92 and 98 Gasoline Are Mixed?
3 Answers
If the vehicle's specified gasoline grade is 92, mixing in 98 gasoline is acceptable, but long-term mixed use is not recommended. However, if the vehicle's specified gasoline grade is 95 or 98, mixing in 92 gasoline will have adverse effects. Long-term use of 92 gasoline in such cases should be avoided, as it increases the frequency of engine knocking and accelerates engine wear. Below are additional details about gasoline: 1. Do not blindly use higher or lower-grade gasoline than recommended, as this can lead to increased carbon deposits. Always follow the manufacturer's recommended gasoline grade for optimal performance. Refueling according to the engine's compression ratio or the vehicle's manual is more scientific, economical, and helps maximize engine efficiency. 2. Gasoline grades indicate the octane rating. For example, 92 gasoline consists of approximately 92% isooctane and 8% heptane. Since isooctane has better anti-knock properties compared to heptane, higher-grade gasoline (with higher octane ratings) offers better anti-knock performance.
Last time I accidentally mixed 92 and 98 octane gas, but it's actually not a big deal. 92 has poorer anti-knock properties while 98 is too expensive - mixing them gives you roughly 95 octane performance. Don't worry too much, just keep driving normally. Next time remember to wait until the tank is nearly empty before refilling with a single octane rating. During the mixed fuel period, avoid prolonged high-RPM driving - low-speed traffic conditions are safest. From my experience, fuel consumption may be slightly higher with mixed fuel, and the engine sound might be a bit muffled, but things basically return to normal after about 300 kilometers. If you're particularly concerned, changing the oil early won't hurt, though it's usually completely unnecessary.
I've also mixed 92 and 98 octane fuel before, and I was really nervous at the time. My mechanic friend told me that this mainly depends on the engine compression ratio, and it has minimal impact on regular commuter cars. The octane rating of the mixed fuel is actually close to 95. Modern ECU computers automatically adjust ignition timing to adapt to different fuel grades. However, I should remind you to pay attention to the engine's condition for the first 200 kilometers after mixing. If you notice sluggish acceleration or strange knocking sounds, switch to higher-octane fuel as soon as possible to flush the tank. But my old Corolla ran fine for half a year with mixed fuel. If you're really worried, go for a professional fuel system cleaning.
