What does the standard number of oil represent?

[VonMalia]

The standard number of oil represents the octane rating of gasoline. Selection basis: The main basis for selecting gasoline grades is the engine's compression ratio. Blindly using high-grade gasoline will not only result in sluggish acceleration during driving, but also fail to utilize its high anti-knock advantage, leading to a waste of money. Therefore, carefully selecting the gasoline grade is crucial. Compression ratio: The primary standard for selecting gasoline grades in cars is the engine's compression ratio, which is also a core energy-saving indicator of modern vehicles. The engine's operation consists of a cyclical motion of "intake - compression - combustion - exhaust - intake" in the cylinders. The compression ratio is the ratio of the cylinder volume when the piston is at its farthest and nearest points in the stroke.

[Harmony]

You often see numbers like 92 and 95 when refueling, right? These actually represent the gasoline's anti-knock index. Simply put, it's the fuel's 'pressure resistance' under the engine's high compression. For example, 95-octane gasoline can withstand compression in the cylinder better than 92-octane without pre-igniting. Why does it matter? If your car requires 95 but you opt for cheaper 92 to save money, the engine might 'cough'—technically called knocking, and over time, even the piston rings could crack from the vibrations. However, don't blindly use higher octane fuel either—like filling an old Jetta with 98, which is just a waste—it won't boost performance and costs more. Remember, checking the fuel cap label is the most reliable way!