Should Regular Cars Use 92 or 95 Octane Gasoline?

[KingstonRose]

The choice of fuel grade should be determined by the compression ratio of the car's engine. The appropriate fuel grade for the vehicle is usually indicated on the inside of the fuel tank cap. If it specifies 92 octane fuel, use 92; if it specifies 95 octane fuel, use 95. Meaning of gasoline grades: The higher the grade, the better the anti-knock performance, allowing it to withstand higher cylinder pressure. There is no difference in composition between 92 and 95 octane gasoline—both are blended from 90 octane crude oil. The only difference is the octane rating. Different octane ratings result in different anti-knock properties. 95 octane gasoline generally has a higher octane rating than 92 octane, providing better anti-knock performance, but it burns relatively slower than 92 octane. Typically, naturally aspirated engines use 92 octane gasoline, while turbocharged engines use 95 octane.

[VonLayla]

Looking at this issue is like debating whether to drink milk or soy milk for breakfast—it all boils down to your car's inherent requirements. The fuel cap usually indicates the manufacturer's recommended octane rating, and for most family cars, 92 octane is perfectly adequate. The engineers have already done the math for you. Over my decade-plus of driving, I've noticed that while 95 octane does offer slightly better anti-knock performance, the difference is negligible in ordinary engines. Once, I filled up with 95 for a long trip, spent over 200 yuan extra on fuel, and didn’t see any noticeable improvement in fuel efficiency. Unless the manual specifically recommends a higher octane, there’s really no need to waste money—saving those extra bucks for a new set of wiper blades is far more practical. Just remember not to mix different octane ratings; wait until the tank is nearly empty before switching.

[DeKaleb]

In terms of combustion efficiency, the main difference between 92 and 95 is the proportion of isooctane, which essentially comes down to their anti-knock capabilities. If your car has a turbocharger or a compression ratio exceeding 10:1, like some German models, 95 octane is necessary to fully unleash its performance. Last time, my neighbor insisted on using 92 in their newly bought compact car, and within just six months, the engine warning light came on. It took cleaning the throttle body and fuel system to fix the issue. However, most modern cars now come with knock sensors, so using 92 in a regular naturally aspirated engine won’t harm the vehicle. The maintenance manual is more reliable than the gas station attendant’s advice, and be cautious not to fall for fuel additive scams at the pump.

[GrantFitz]

This is a hot topic among us young car modifiers. In theory, 95-octane fuel allows RPMs to climb faster, especially during hill climbs and hard acceleration. We've tested it on Civics and Fits - 95-octane does slightly reduce fuel consumption, saving about 0.5L per 100km. But do the math and reality hits: with current fuel price differences of 0.5 yuan, the savings barely buy a bottle of water. Older cars need caution - my dad's old Excelle developed idle vibration after switching to 95, which the mechanic attributed to incomplete combustion causing carbon buildup. For modified cars, you'll only see real benefits from higher octane fuel if you also adjust ignition timing. For commuter cars, it's not worth the hassle - choosing a reputable gas station brand matters much more than octane rating.