What does the engine oil specification 20W-50 mean?

[DeEmmanuel]

The engine oil specification 20W-50 represents the oil viscosity, where W stands for WINTER, indicating its use in winter. The number 20 before W indicates the low-temperature viscosity. The smaller the number, the better the fluidity at low temperatures, resulting in better cold-start performance. The number 50 refers to the viscosity at 100°C. The larger the number, the higher the viscosity and the better the high-temperature resistance. Below are related explanations: 1. Winter oil specifications are as follows: 0W, 5W, 10W, 15W, 20W, 25W. The symbol W stands for winter. 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 oil specifications are as follows: 20, 30, 40, 50. The larger the number, the higher the viscosity and the higher the applicable maximum temperature. 3. All-season oil specifications are as follows: 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, the larger the number representing the summer part, the higher the viscosity, and the wider the applicable temperature range.

[DeOscar]

Having worked in the automotive repair industry for many years, I've encountered countless cases involving engine oil. The 20W-50 grade actually indicates the oil's performance at different temperatures. The 'W' stands for Winter, and the number '20' refers to the low-temperature viscosity, meaning the oil flows smoothly when temperatures drop to -20 degrees Celsius, making engine starts easier without hesitation. The '50' indicates high-temperature viscosity, maintaining stable oil film thickness at 100 degrees Celsius to protect the engine from wear. Thicker oils like this are suitable for older vehicles or cars driven year-round in tropical regions, as larger engine clearances require stronger lubrication. However, newer or precision-engineered vehicles might benefit more from thinner oils for better fuel efficiency. Always consult the owner's manual when selecting oil, as mismatches can lead to increased fuel consumption or accelerated engine wear. That's why I often advise car owners to change oil regularly based on seasons and driving conditions.