Will using 98 octane gasoline instead of 95 octane harm the car?
3 Answers
It may potentially harm the vehicle. Below are the differences between 95 and 98 octane gasoline: 1. Different octane ratings: The octane number simply indicates the level of octane in the gasoline. The octane rating is determined by comparing the fuel's knock intensity with a standard mixture of isooctane and n-heptane. The percentage of isooctane in the standard fuel that produces the same knock intensity as the sample is the octane rating of the sample. 95 octane gasoline consists of 95% isooctane and 5% n-heptane, while 98 octane gasoline consists of 98% isooctane and 2% n-heptane. 2. Different anti-knock combustion capabilities: The higher the octane rating, the better the anti-knock combustion performance. 95 octane gasoline: Moderate anti-knock combustion capability. 98 octane gasoline: Higher anti-knock performance and better power output. 3. Price differences: Generally, the higher the octane rating, the better the quality of the gasoline, and thus the more expensive it is. 95 octane gasoline: Mid-grade fuel. 98 octane gasoline: Higher quality with fewer harmful substances and lower exhaust emissions, hence the higher price.
I remember researching this issue before, and it actually doesn't harm the car. When a car is labeled for 95-octane gasoline, it means it requires a minimum of 95 octane to prevent engine knocking. 98-octane gasoline has a higher octane rating, which means better anti-knock performance, so putting it in the car can actually make the engine run more smoothly. Modern cars have computer control systems that automatically adjust ignition timing to adapt to different fuel grades, so using 98-octane might even slightly improve the car's responsiveness. However, this benefit is usually very minor, and you'll hardly notice any difference during normal driving. The biggest issue is that 98-octane fuel is much more expensive. If your car is designed for 95-octane, you're just wasting money, and there's no need to do this. I recommend sticking with 95-octane unless your car is a high-performance vehicle—it's more cost-effective and environmentally friendly. If you accidentally use the wrong fuel, don't worry; once or twice won't cause any issues, but in the long run, it's best to follow the manual. In short, it's safe and harmless—just a bit harder on your wallet.
I drive a car that requires 95-octane fuel. Once, the gas station only had 98-octane, so I had to give it a try. There was no noticeable difference in driving—the engine remained just as quiet and smooth, with even a slight improvement in acceleration when going uphill. Later, I asked my mechanic friend about it. He explained that higher-octane fuel has better anti-knock properties and might offer better engine protection under high-temperature conditions, but in most cases, it's overkill. The key point is that it won’t damage the engine because the vehicle’s ECU can intelligently adjust parameters to adapt to different fuel qualities. The downside is that it costs nearly one yuan more per liter—I ended up spending over 20 yuan extra on that trip for no real benefit. Now, I always check the label and choose the correct fuel grade—it saves money and gives me peace of mind. If you frequently use higher-octane fuel, the ECU may learn and adjust, potentially leading to minor carbon buildup, but this isn’t a major issue; just perform regular cleaning. Overall, an occasional mistake is fine, but it’s best to develop the habit of checking the fuel grade at the pump.
