What does 10w40 engine oil mean?

[Xavier]

Synthetic engine oil 10w-40 refers to the SAE standard viscosity value of the oil. The "W" stands for winter, and 10W represents resistance to external low temperatures of -25°C. Below is a detailed introduction to the types of engine oil models: 1. High-temperature type (such as SAE20-SAE50): The number indicates the viscosity at 100°C, with higher numbers representing higher viscosity. 2. Low-temperature type (such as SAEOW-SAE25W): W indicates it is only for winter use, and the smaller the number, the lower the viscosity and the better the low-temperature fluidity. 3. All-season type (such as SAE15W/40, 10W/40, 5W/50): Indicates that the viscosity grade at low temperatures meets the requirements of SAE15W, 10W, and 5W respectively, and the viscosity grade at high temperatures meets the requirements of SAE40 and 50 respectively, making it suitable for both winter and summer use.

[McPaislee]

The number combination 10W40 for engine oil is quite straightforward to explain. 10W represents better fluidity in winter at low temperatures, making it easier for the car to start without getting stuck. It can even be used at temperatures as low as -30°C, preventing the engine from suffering. The 40 indicates high-temperature viscosity, ensuring that even during high-speed driving or in summer when the engine gets hot, a lubricating film is maintained to protect components from wear. In daily driving, I've found this type of oil quite convenient in places with seasonal changes, eliminating the need for frequent seasonal oil changes and reducing hassle. However, it's important not to choose the wrong viscosity—I once tried using the wrong oil, and the engine noise increased while fuel consumption went up, which was really frustrating. I recommend checking your car's manual, as it usually specifies the suitable type of engine oil. Don't blindly trust those so-called 'universal' advertisements. Proper maintenance can save you repair costs, so always check the viscosity rating when changing oil to ensure it matches your car's requirements.

[Cox]

As the SAE viscosity grade for engine oil, 10W40 in my view has the '10W' representing 'Winter', indicating low-temperature fluidity. The number 10 corresponds to a starting capability at -30°C, ensuring the engine isn't hindered in cold weather. The '40' denotes high-temperature viscosity thickness at 100°C, maintaining stable lubrication. Through daily driving, I've found this oil suits most regular vehicles, especially in temperate zones, offering a balanced response to climate variations. Oil that's too thick or thin causes issues – overly thin increases fuel consumption, while excessive thickness worsens acceleration, affecting driving feel. So during routine oil changes, I always advise friends not to focus solely on brands; viscosity matching is crucial, along with vehicle age – older cars might need slightly higher viscosity. Developing a habit of checking dipstick levels and oil color enables early detection of abnormalities.

[CollinLee]

In 10W40 engine oil, the 'W' stands for winter, '10' indicates good fluidity at low temperatures for smooth starts, and '40' means sufficient viscosity at high temperatures to protect the engine. Don't just rely on ads when choosing oil; it must match your vehicle's condition. 10W40 is commonly used for general household cars all year round. Using the wrong oil can lead to rapid engine wear. More maintenance means fewer worries.