What does the octane number of gasoline mean?
2 Answers
Gasoline's octane number represents its anti-knock performance. The gasoline grade commonly referred to indicates its octane number. Petroleum consists of various alkanes, among which isooctane has good anti-knock properties while n-heptane performs poorly. 90-grade gasoline means it contains 90% isooctane and 10% n-heptane; 92-grade gasoline contains 92% isooctane and 8% n-heptane. The higher the grade, the more isooctane content, and the stronger the gasoline's anti-knock performance. To understand it simply, lower-grade gasoline like 92 or 93 is more easily ignited during piston operation, while higher-grade gasoline like 95 or 98 is relatively harder to ignite.
I've been driving for over a decade and often hear people talk about gasoline octane ratings. Simply put, the octane number indicates a fuel's anti-knock performance—the higher the value, the more resilient it is. It's like giving your car alcohol of varying strengths; some cars with 'Erguotou' constitutions are fine with 92 octane, while turbocharged cars with their fiery dispositions need at least 95 octane to avoid acting up. Engine knocking is the worst—it's when the fuel ignites prematurely before the piston reaches the top, creating a pinging sound like firecrackers in the engine. Using the wrong octane not only wastes fuel but can even crack piston rings. Every time I switch cars, I first check the fuel cap—whatever number is written there is the one I stick to, and it's never failed me.
