Should Older Cars Use 5W30 or 5W40?

[DiValentina]

For older cars, whether to use 5W30 or 5W40 generally depends on the engine's condition and cylinder wear. Older engines often require oil to assist in sealing, so 5W40 is usually recommended. However, the specific choice should consider the vehicle model, the environmental temperature of the region where the car is used, and the oil type recommended in the vehicle's maintenance manual. More detailed information is as follows: 1. There are many types of oil grades, and different grades indicate different oil performances. Taking 5W-30 as an example, the '5' represents that the oil is suitable for temperatures above -25°C. If it's '10', it means above -20°C. The smaller the number before the 'W', the better the low-temperature fluidity. This makes it more suitable for northern winters, offering better cold-start performance. 'W' stands for winter, indicating that the oil has a wide applicable temperature range and can be used all year round. 2. The number after 5W-30 is the viscosity index, which refers to the oil's viscosity at 100°C being 30. The larger the number, the higher the viscosity, providing better protection for the engine at high temperatures. However, the appropriate oil grade should be chosen based on different driving conditions and vehicle models. 3. The main differences between 5W30 and 5W40 are: 5W-30 has relatively better fluidity, more effectively reducing fuel consumption and allowing the engine to dissipate heat faster and more efficiently. However, for some older cars, using 5W-30 may result in slightly louder engine noise, and some engines that strictly require 5W-40 may experience higher than normal fuel consumption if 5W-30 is used instead. At high temperatures, 5W-40 offers better oil stability.