What Do the Numbers in Motor Oil Represent?
2 Answers
The numbers in motor oil represent the following: Winter: Winter oil grades are: 0W, 5W, 10W, 15W, 20W, 25W. The symbol W stands for Winter, and the smaller the number before W, the lower the low-temperature viscosity, the better the low-temperature fluidity, and the lower the applicable minimum temperature. Summer: Summer oil grades are: 20, 30, 40, 50. The larger the number, the higher the viscosity and the higher the applicable maximum temperature. All-Season: All-season oil grades are: 5W/20, 5W/30, 5W/40, 5W/50, 10W/20, 10W/30, 10W/40, 10W/50, 15W/20, 15W/30, 15W/40, 15W/50, 20W/20, 20W/30, 20W/40, 20W/50. The smaller the number representing the winter part, and the larger the number representing the summer part, the higher the viscosity and the wider the applicable temperature range.
I encountered this issue when I first started driving. Seeing numbers like 10W-40 on the oil bottle really confused me. Later, I learned that those numbers represent the oil's viscosity. The number before the W, like 10, indicates the oil's flow capability at low temperatures—the smaller the number, the easier the car starts in cold weather, avoiding winter starting problems. The number after the W, like 40, means the oil is thicker at high temperatures, protecting the engine's internal components from wear. This directly affects the car's lifespan, so I always check the vehicle's manual when buying oil—choosing the right one saves money and ensures peace of mind. Otherwise, the engine can easily get damaged. I adjust the oil type seasonally—using a higher number in summer and a lower one in winter. Never skimp on quality—oil is the lifeblood of a car. Take care of it, and the car will run smoothly for a long time.
