Can 15w40 engine oil be used in winter?

[VonCassandra]

15w40 engine oil can be used in winter in southern regions, but it is not suitable for areas in the north where winter temperatures drop below -20 degrees Celsius. The number before 'w' indicates the oil's low-temperature fluidity. The smaller the number, the better the low-temperature fluidity, and the lower the applicable minimum temperature. '15' means the oil is suitable for a minimum temperature of -20 degrees Celsius. The effects of not changing engine oil for a long time include: 1. The oil becomes ineffective and deteriorates, increasing wear and damage to engine components; 2. Reduced sealing effect, causing the oil to become watery and lose its sealing function; 3. Decreased cooling effect; 4. Accumulated impurities can corrode internal engine parts; 5. Loss of lubrication performance in bearings and lubrication and cooling functions in mechanical transmission components, affecting the vehicle's optimal driving condition; 6. Damage to the engine; 7. Formation of sludge leading to engine failure.

[DelMaddox]

As a seasoned driver with over a decade of experience in southern regions, I've used 15W-40 oil during winters without major issues. Winter temperatures there usually stay above 0°C, making cold starts manageable—though the engine works slightly harder, it's fine for short trips. However, back in my northern hometown where temperatures drop to -10°C or lower, this oil becomes risky: the engine often requires multiple cranks to start, sometimes with abnormal noises. My advice is to check local minimum temperatures before winter—if below -10°C, switch to lower-viscosity oils like 5W or 0W (e.g., 0W-20) for smoother cold starts and reduced engine wear. The "15W" on oil labels indicates cold-start performance—higher numbers mean thicker viscosity, problematic in extreme cold. Always consult mechanics during oil changes to avoid costly engine damage. While suitable for mild climates, this oil demands caution in severe cold.

[VanWillow]

Having lived in Northeast China for many years, I fully understand the critical importance of oil viscosity in winter. 15w-40 oil tends to thicken and become viscous in low temperatures. When starting the engine at around -15°C, the oil struggles to lubricate components quickly, which can lead to engine vibration or even wear. In comparison, I highly recommend using lower viscosity oils like 0w-30 or 5w-40 during winter, especially for frequent drivers, as they can reach optimal lubrication faster to protect the engine. In my neighborhood, I often see neighbors spending hundreds on repairs due to using the wrong oil – quite a waste. From experience, in temperate regions like areas south of the Yangtze River, 15w-40 might barely suffice near freezing point, but in colder temperatures, it's best to change the oil in advance. Every seasonal transition, I check the oil dipstick to confirm its fluidity. Remember, engine oil protects your engine's lifespan – upgrading to better oil is far wiser than trying to save a few bucks.

[IsaacFitz]

From the perspective of engine oil performance, the "15w" in 15w-40 indicates low-temperature fluidity. A higher number becomes a drawback in harsh winters. Below 0°C, the oil thickens, leading to insufficient lubrication during startup and increased engine strain. In practical applications, I've tested in my garage: at low temperatures, older cars using 15w-40 exhibit noticeably slower starts and rougher engine sounds compared to lower-viscosity oils. Generally, it's advised to avoid using 15w-40 when winter temperatures drop below -10°C; switching to a 5w grade is safer. Before selecting oil, consult your vehicle manual or online tools to ensure temperature compatibility and prevent sudden failures. Simply put, it's usable in winter but with limitations—don't gamble with it in extreme cold.