What Do the Numbers on Motor Oil Mean?
4 Answers
The numbers on motor oil represent the following meanings: 1. 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. 2. Summer: Summer oil grades are: 20, 30, 40, 50. The larger the number, the higher the viscosity and the higher the applicable maximum temperature. 3. 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.
The numbers on engine oil, like 5W-30, represent the viscosity grade of the oil for your car's engine. Simply put, they indicate how the oil flows to protect the engine at different temperatures. The first part with a 'W', such as 5W, refers to the oil's flow capability in cold winter temperatures; the lower the number, the easier it is to start the engine in cold weather, preventing hard starts. The latter part, like 30, indicates the oil's ability to maintain thickness at high temperatures; the higher the number, the better it prevents wear during high-speed driving in hot conditions. Having driven many cars, I've found that choosing the wrong viscosity can lead to increased engine noise, higher fuel consumption, and even reduced engine lifespan. The best approach is to check your car's manual—manufacturers usually recommend specific viscosities, such as 0W-20 for cold regions or 10W-40 for subtropical areas. The type of oil (synthetic or mineral) affects performance but doesn't change the meaning of these numbers. Remember, regular oil changes are crucial—they extend your engine's durability.
As an average car owner, understanding oil viscosity numbers gives me peace of mind when driving. For example, in 5W-30, the 5W indicates good low-temperature fluidity, making it suitable for winter starts; while 30 represents high-temperature viscosity, protecting the engine during hot weather operation. If the numbers are too high like 20W-50, cold starts become difficult; if too low like 0W-16, it may not provide sufficient protection at high speeds. I once used the wrong oil and noticed increased engine noise and higher fuel consumption. I recommend everyone follow their vehicle's manual when selecting oil—don't cut corners with cheap oils. Additionally, newer oil specifications like SP or SN indicate additive quality, but the core numbers still represent viscosity. Discussing this during maintenance can prevent major repair issues, saving both hassle and money.
Engine oil numbers like 10W-40 are directly related to engine protection. 5W is the low-temperature grade, with W standing for Winter; the smaller the number, the better the flow in cold conditions. 40 is the high-temperature grade, where a larger number means the oil stays thicker and resists thinning under high heat. This design prevents engine wear and can also save some fuel. A reminder for beginners: using the wrong oil can lead to noise and hard starts. Always check your vehicle's manual for the right choice—don't just follow the crowd when buying.
