How to Distinguish Engine Oil Viscosity?

[DelPiper]

Engine oil viscosity can be distinguished by the following methods: 1. AB Series: For gasoline and light-duty diesel engines; 2. C Series: Catalyst-compatible engine oils; 3. E Series: Heavy-duty diesel engine oils. The functions of engine oil include: 1. Cooling and temperature reduction; 2. Sealing and leak prevention; 3. Cleaning and purification; 4. Shock absorption and buffering; 5. Lubrication to reduce wear; 6. Rust and corrosion prevention; 7. Component protection. Engine oil, also known as engine lubricant, is composed of base oil and additives. Base oil is the main component of lubricating oil, determining its fundamental properties, while additives compensate for and improve any deficiencies in the base oil's performance.

[CharlesLynn]

Understanding engine oil viscosity is as simple as reading the numbers on the package. Take 5W-30 for example: The number before the W indicates cold temperature performance - a 5 means the oil can flow normally at -30°C. The number after the W (30) shows high-temperature performance - the viscosity at 100°C, where higher numbers mean thicker oil. Newer cars typically use thinner oils like 20 or 30 for better fuel efficiency and smooth operation, while older engines with larger gaps benefit from thicker 40 or 50 grades that form better protective layers. Choose higher high-temperature numbers for hot summers or frequent highway driving, and lower cold-temperature numbers for winter in cold regions. Don't fall for the myth that thicker is always better - always follow your manual's recommended grade, as using the wrong viscosity can accelerate wear or increase fuel consumption.

[Weston]

With over 20 years of driving experience, I've learned two key points about oil viscosity: The number before the W relates to temperature, and the number after W relates to the vehicle's condition. For example, 0W-20 means 0W indicates it won't freeze even at -35°C, making cold starts smooth in winter; 20 means it's thin like water at high temperatures, ideal for new Japanese cars. If you see 10W-40, it's typically for older German cars, needing higher viscosity when warmed up to support the engine. Don't be fooled by repair shops when changing oil—always check the manual. Once I mistakenly used 40 viscosity oil, and my fuel consumption increased by more than half a liter; switching back to 30 viscosity fixed it. Remember, viscosity grades aren't quality ratings—both synthetic and mineral oils can come in different viscosities.

[EllaRose]

Distinguishing oil viscosity is actually quite simple, just look at the SAE rating. The smaller the number before the W, the better the low-temperature fluidity – 5W is more freeze-resistant than 10W. The number after W indicates high-temperature viscosity, with larger numbers meaning thicker oil film. New cars should use low viscosity like 0W-20 for fuel efficiency and quiet operation; older cars are better suited for 5W-40 to prevent oil burning. In northern winters, it's best to use 0W-rated oil, while in southern regions with year-round temperatures above 30°C, consider 40 viscosity. Don't just follow recommendations during maintenance – checking the owner's manual is most accurate. Using the wrong viscosity may trigger warning lights. Last time, my neighbor used 20 viscosity in an older car and experienced oil burning, but switching back to 40 viscosity solved the problem.

[LaMariana]

The combination of letters like 5W-30 on an oil bottle is essentially its viscosity ID. The 'W' stands for winter, and the number before it indicates cold-start performance, with 0W corresponding to -35 degrees Celsius. The number after the dash represents high-temperature performance, with 30 being commonly used in new Japanese and Korean cars. A simple rule to remember: the larger the number, the thicker the oil. For high-altitude areas or frequent long-distance driving, a 40 viscosity is recommended—it flows less easily but offers better protection. For daily commuter cars, 20 viscosity is the most cost-effective, saving half a liter of fuel per 100 kilometers. Don't blindly trust factory oil; as long as the grade matches, both mineral and synthetic oils can be used. However, mixing different viscosities can disrupt the formula balance, so it's best to completely drain the old oil during maintenance.