What Does Engine Oil Grade Mean?
3 Answers
Engine oil grade consists of two parts: classification and viscosity specification, which generally indicate viscosity and quality. The viscosity of engine oil is often identified using SAE grades. SAE is the abbreviation for the "Society of Automotive Engineers" in English. The "W" stands for winter, and the smaller the number before it, the better the low-temperature fluidity of the oil, indicating a lower usable environmental temperature. The number after it represents the oil's high-temperature resistance. Engine oils are specifically classified into 4 types for summer use, 6 types for winter use, and 16 types for all-season use. The summer oil grades are: 20, 30, 40, and 50, with higher numbers indicating greater viscosity. The winter oil grades are: 0W, 5W, 10W, 15W, 20W, and 25W.
The oil grade is the viscosity rating label of the motor oil, commonly seen in formats like 5W-30. It consists of two parts: the number plus W indicates low-temperature performance, where W stands for winter, and a smaller number like 5 means lower viscosity and better fluidity at low temperatures, making cold starts easier. The number after W, such as 30, refers to the viscosity at high temperatures, ensuring lubrication and preventing wear. Choosing the right grade depends on climate and vehicle type: in cold regions, use a lower first number like 0W or 5W for easier starts, while in hot areas, avoid too high a second number to prevent excessive fuel consumption. With my extensive driving experience, when I lived in the north, I used 10W oil and often had trouble starting in winter, but switching to 5W made starts effortless. Choosing the wrong oil not only affects driving but can also damage engine longevity, so always refer to the owner’s manual and avoid random trials. Targeted maintenance saves unnecessary hassle.
Engine oil grades are defined based on the SAE standard, such as 10W-40 representing two viscosity values. The 10W part tests low-temperature flow, where a lower number like 10 indicates faster flow at sub-zero temperatures for easier cold starts. The 40 part refers to high-temperature viscosity at 100°C, ensuring better protection for engine components. If viscosity is too low, lubrication may be insufficient under high loads, leading to wear; if too high, it increases friction and fuel consumption. Choosing the right grade depends on engine design: newer cars benefit from low-viscosity oils like 0W-20 for efficiency, while older vehicles may need higher grades like 15W-50 to compensate for wear. Research shows using the wrong grade can cause oil to degrade prematurely, leading to frequent maintenance and wasted money. Always refer to the manual—different vehicles have varying needs, and using the correct oil maximizes protection and extends engine life.
