What Are the Engine Oil Grades for Summer Use in Cars?
4 Answers
The viscosity grade at 100 degrees is the primary reference for summer engine oil. The summer engine oil grades for cars include: 20, 30, 40, 50. The larger the number, the higher the viscosity and the higher the maximum applicable temperature. Winter engine 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 minimum applicable temperature. Engine oil, also known as motor lubricant, serves functions such as lubrication and wear reduction, auxiliary cooling, sealing and leak prevention, rust and corrosion protection, and shock absorption for the engine.
When choosing engine oil for summer, I mainly look at the high-temperature viscosity index, which is the number after the oil grade, like the 40 in 5W-40. In the south, summer temperatures can easily reach 40°C, and the engine is prone to overheating. In such cases, using oil with higher viscosity is more reliable, such as 10W-40 or 5W-40, as it forms a thicker oil film at high temperatures, protecting parts from wear. Last year, my car’s temperature gauge spiked in traffic, but after switching to a full synthetic oil with a 40 viscosity, the situation improved noticeably, and even cold-start noise reduced. However, for older cars or those frequently used for long-distance driving, it’s best to check the manual first. German cars generally use 40 viscosity, while Japanese cars can also use 30. I’ve also noticed that full synthetic oils from major brands offer better high-temperature resistance and stronger carbon deposit cleaning effects. Although they cost a bit more, they’re worth the peace of mind.
The number after W in the oil grade is crucial for summer, as it indicates high-temperature protection capability. For my daily commute, I prefer 5W-40 in summer, which balances cold-start performance and high-temperature protection. During my last maintenance, the technician mentioned that low viscosity in hot weather can easily lead to oil film rupture, causing cylinder scoring. Grades like 5W-30 are more suitable for cooler regions, while 40 is safer in southern areas. Remember to check the oil grade markings, such as SP or SN, which offer better high-temperature oxidation resistance. Additionally, with more rain in summer, I choose oils with water-resistant additives to prevent emulsification. Don't exceed an oil change interval of 8,000 kilometers, especially for older cars. I check the dipstick every six months and change the oil early if it appears dark.
As a car novice, I just figured out the meaning of engine oil grades. For summer oil selection, focus on the suffix number—choose between 30 to 50, with 5W-40 recommended for daily driving. The mechanic taught me that high summer temperatures thin the oil, and higher viscosity offers better protection, but it must be balanced with the car's age and mileage. My domestic SUV originally required 5W-30, but after highway driving last summer, the engine sound became noticeably muffled. Switching to 5W-40 made it much quieter. The mechanic warned that viscosity changes shouldn't be too drastic, like jumping from 20 directly to 50, as it could harm the engine—adjust gradually. Synthetic oil is also better for extreme heat, with less evaporation and stable fuel consumption. I now stick to semi-synthetic oil for the long southern summers.
