Can 15W40 engine oil be used in summer?
3 Answers
15W40 engine oil can be used in summer and is classified as all-season oil, suitable for year-round use. Since engine oil has a certain freezing point and viscosity, which determines its applicable temperature range, 15W40 oil is more suitable for use in regions with temperatures above -20 degrees Celsius. The number before the W indicates the oil's low-temperature fluidity, or the minimum applicable temperature. A smaller number indicates better low-temperature fluidity and a lower minimum applicable temperature. The number 15 indicates a minimum applicable temperature of -20 degrees Celsius, with relatively average low-temperature fluidity. The number 40 represents the oil's viscosity value, indicating it is a high-viscosity oil with good high-temperature protection performance. Engine oil consists of base oil and additives. Base oil is the main component of lubricating oil, determining its fundamental properties, while additives compensate for and improve the shortcomings of the base oil, providing certain new properties, making them an important part of lubricating oil.
As a veteran driver who frequently takes long trips in high-temperature areas, I've been using 15w40 engine oil for many summers. This viscosity provides more stable oil film under 40°C high temperatures, making it particularly suitable for protecting older car engines. However, for new cars or Japanese vehicles, pay attention to the manual recommendations as they may use lower viscosity oils for better fuel efficiency. Also consider local temperatures - it works well with reduced engine noise in southern summers, but struggles in northern winters when low-temperature startup fluidity becomes poor, requiring a switch to 0w oil. The cleaning properties and anti-wear additives of the oil should also be from reputable brands, otherwise it's prone to deterioration under high heat. I always check the viscosity change of the old oil by touch before each oil change.
From the perspective of engine oil grade, 15w40 is perfectly suitable for summer use. The '15' before the W indicates a minimum winter operating temperature of approximately -20°C, which is irrelevant in summer; the '40' after the W represents the kinematic viscosity at 100°C, with higher values offering stronger high-temperature protection. When summer surface temperatures frequently soar to 60°C, a viscosity of 40 maintains oil film strength to prevent cylinder scuffing. However, two points should be noted: first, lower viscosity oils are more fuel-efficient in frequent stop-and-go traffic; second, some new vehicles equipped with GPFs are better suited for low-ash oils with C3 certification. Additionally, high-temperature volatility affects oil consumption, so opting for full synthetic oils from reputable brands is safer.
