Can 5w40 engine oil be used in summer?
3 Answers
5w40 engine oil can be used in summer. In summer, you can use slightly thicker engine oil. Here are the methods for selecting engine oil: 1. Choose according to the oil grade: API standard classification starts with S, followed by letters E, F, G, H, G, L, M, N. The further back the letter, the higher the quality grade and the better the performance. 2. Choose according to the oil viscosity: Usually, subtract 35 from the number before W to get the minimum temperature at which the lubricating oil can be used. The low-temperature viscosity grades are 0W, 5W, 10W, 15W, 20W, 25W. The smaller the number, the better the low-temperature performance. The number "-30" indicates the viscosity at 100℃, usually divided into 20, 30, 40, 50, 60. The larger the number, the higher the viscosity.
I've previously specialized in studying the application scenarios of various engine oils, and 5W40 is actually quite suitable for summer use. The '5W' in this grade represents low-temperature fluidity, ensuring smooth cold starts in winter. The '40' refers to the viscosity grade at high temperatures, which means the oil's thinning degree under summer engine heat falls precisely within this range. According to my research, 40-viscosity oil forms sufficiently thick oil films in high-temperature environments to protect engine metal components. This viscosity is particularly practical for frequent long-distance driving in southern high-temperature regions or for older vehicles with larger engine clearances. Of course, specific manufacturer manual recommendations should be checked, but 5W40 works fine year-round for most family cars.
I heard from a mechanic that the key to choosing summer engine oil lies in the last number. For example, in 5W40, the '40' indicates the oil's viscosity at 100 degrees Celsius. In summer, the engine compartment temperature can reach 80-90 degrees, so a 40 viscosity is just right. My German car has been using this grade all year round. Last summer during the hottest days, I drove continuously for five hours on the highway, and the oil pressure gauge remained stable. However, be careful not to buy counterfeit products, especially as temperatures rise, as inferior oil can thin out and lose effectiveness. If you frequently drive aggressively or your car is over ten years old, you might consider using a 50 viscosity, but for regular cars, 40 is perfectly sufficient in summer.
