Should a Naturally Aspirated Engine Use 92 or 95 Octane Gasoline?

[MacQuinn]

This depends on the type of engine and its compression ratio. If the engine has a high compression ratio, higher-octane gasoline should be used; if the compression ratio is low, lower-octane gasoline is sufficient. The details are as follows: 1. For household cars equipped with naturally aspirated engines, 92-octane gasoline is recommended. This is because household vehicles typically use small-displacement naturally aspirated engines with relatively low compression ratios, and 92-octane gasoline meets their operational requirements. 2. There is no difference in fuel quality between 92 and 95-octane gasoline—only their octane ratings differ. 92-octane gasoline consists of 92% isooctane and 8% n-heptane, while 95-octane gasoline contains 95% isooctane and 5% n-heptane. Compared to 92-octane, 95-octane gasoline has a higher octane rating, providing better anti-knock performance. 3. Anti-knock performance refers to gasoline's ability to resist knocking during combustion in the engine. Using gasoline that does not meet the specified octane rating may cause knocking due to incomplete combustion.