What is the introduction of lubricating oil viscosity?

[JackLee]

The viscosity grade of engine oil is closely related to the vehicle model and local temperature. Below is an introduction to its connection with vehicle models and local temperatures: 1. Vehicle model: Japanese cars prefer low-viscosity oil, while German cars prefer high-viscosity oil. 2. Local temperature: (1) 0W suitable temperature — -35°C (polar regions) (2) 5W suitable temperature — -30°C (northeast and northwest regions) (3) 10W suitable temperature — -25°C (north-central and southwest regions) (4) 15W suitable temperature — -20°C (north-central and southwest regions) (5) 20W suitable temperature — -15°C (areas south of the Yellow River and north of the Yangtze River) (6) 25W suitable temperature — -10°C (subtropical regions)

[LeGianna]

I've been driving for over a decade and choosing oil viscosity is quite particular. Simply put, viscosity refers to how easily the oil flows. For a grade like 5W-30, the number before the W represents low-temperature fluidity—the smaller the number, the smoother the cold starts. The number after the W indicates high-temperature viscosity—the larger the number, the thicker the oil film. I usually use low-viscosity oil like 0W-20, which ensures quick starts in winter, better fuel efficiency, and quieter engine noise on highways. However, older cars need higher viscosity oil like 10W-40, otherwise, poor sealing can lead to oil burning. Last year, I helped a neighbor check his car—he had used the wrong viscosity oil, which caused a spike in fuel consumption and triggered a warning light. Nowadays, new engines generally recommend low-viscosity oil, but never change the grade arbitrarily. Always refer to the vehicle manual's recommended values. Choosing the wrong viscosity can lead to wasted fuel at best or engine damage at worst.

[SanAlice]

I've found that oil viscosity is crucial for engine protection. The viscosity level directly affects oil film thickness, just like dressing engine parts—too thin and it can't withstand friction, too thick and it restricts movement. Every oil change, I scrutinize labels like 5W-30: the first number indicates good low-temperature flow (quick lubrication even at -20°C), while the higher second number ensures strong high-temperature protection (no oil film breakdown during summer road trips). Once, using higher viscosity oil noticeably slowed acceleration and increased fuel consumption by over half a liter. Now I adjust viscosity seasonally—20-weight for winter, 30-weight for summer. Brand differences matter too—same grade oils can vary by 10% in actual viscosity. After testing three brands, I confirmed this impacts throttle response.

[DiHannah]

When changing engine oil, I pay the most attention to the viscosity parameter. Simply put, it's the grading of the oil's fluidity. For example, in 10W-40, the smaller the number before the W, the better it performs in cold weather, providing faster cold-start protection. The larger the number after the W, the better it withstands high temperatures. During my last maintenance, the mechanic said German cars should use 40 viscosity oil, while Japanese cars are better suited for 20 viscosity. Using the wrong viscosity can lead to abnormal oil pressure. I personally experienced a situation where the engine sound became muffled after using higher viscosity oil, and it only returned to normal after switching back to the manufacturer-recommended viscosity. Viscosity also affects fuel consumption—higher viscosity means thicker oil, requiring the engine to work harder, which can result in up to a 5% difference in long-term fuel costs. Now, I regularly check the dipstick and change the oil early if it becomes too thin, as viscosity degradation can affect lubrication performance.

[IsabelleLee]

My car has run 80,000 kilometers, and I increasingly feel that the oil viscosity needs to be precisely matched. Viscosity essentially reflects the oil's resistance to flow. The number before the 'W' in the grade determines cold-start performance—lower numbers mean the oil can still pump quickly in sub-zero conditions. The number after the 'W' relates to high-temperature protection capability. Currently, my older car uses 5W-40 viscosity, one grade higher than when it was new, because increased engine clearances can cause low-viscosity oil to burn off. I once tried switching to 30 viscosity, but it consumed half a liter of oil in just 3,000 kilometers. When changing oil regularly, pay attention to the condition of the old oil—darkened and thinned oil definitely indicates reduced viscosity. Additionally, viscosity affects cold-start wear; using a 0W grade in winter can reduce dry friction by 70%, effectively extending engine life.

[AlessandraLee]

I found that choosing the right oil viscosity can really save fuel. Low-viscosity oils like 0W-20 have less flow resistance, making the engine run more smoothly, and actual tests show they save 0.8 liters per 100 kilometers compared to high-viscosity oils. However, viscosity can't be infinitely low. Once I tried oil that was too thin, and at high speeds, the oil temperature rose, causing the oil film to thin, and the engine even produced slight knocking sounds. Now I strictly adhere to the viscosity range specified in the vehicle manual, keeping Japanese cars at 20 viscosity and German cars at 30 or 40 viscosity. Seasonal changes must also be considered. In summer, I switch to SAE40 grade due to high temperatures, and in winter, I switch to 30. Even with the same grade, different brands of oil can have actual viscosity differences. I insist on using certified brands to avoid lubrication effects being affected by viscosity deviations.