What is the difference between 95-octane and 92-octane gasoline?
2 Answers
The difference between 95-octane and 92-octane gasoline lies in their octane rating: 95-octane gasoline consists of 95% isooctane and 5% n-heptane, while 92-octane gasoline is composed of 92% isooctane and 8% n-heptane. The compression ratio of a car engine is set according to the octane rating of the fuel used. The compression ratio is an important structural parameter of the engine, representing the ratio of the gas volume when the piston is at the bottom dead center at the start of compression to the gas volume when the piston is at the top dead center at the end of compression. The function of the engine is to convert the thermal energy of gasoline into mechanical energy by burning the expanding gas in a sealed cylinder to push the piston and perform work.
When I first started driving, I was also confused about 92 and 95 octane gasoline. It wasn’t until I drove several different cars that I figured it out. 92 octane is cheaper, but sometimes after filling up, the engine makes a ‘knocking’ sound during acceleration, like small stones tapping. The mechanic said this is called engine knock, and over time it could damage the engine. As for 95 octane, it feels smoother, especially when starting a new car—the noise is less, and the drive is more comfortable. This is mainly because 95 octane has better anti-knock properties, making it suitable for engines with higher compression ratios. Price-wise, 95 octane costs about 1-2 yuan more per liter than 92, adding up to 30-40 yuan more per tank. For daily commuting, 92 is fine, but for long trips or high-end cars, 95 is recommended to protect the engine. I think choosing the right octane depends on the car’s manual—don’t cut corners to save money and risk damaging the engine.
