Can 10W-40 engine oil be used in winter?

[LeElliana]

10W-40 can be used in winter. Here is the relevant introduction about engine oil: 1. Mineral oil: Mineral oil is the remaining oil after gasoline and heavy oil are extracted from petroleum. In fact, mineral oil is also a natural oil with many impurities. It is cheaper compared to semi-synthetic oil and fully synthetic oil, but has poor lubrication performance for the engine and a short service life. 2. Semi-synthetic oil: Semi-synthetic oil is between mineral oil and fully synthetic oil. It contains a large number of anti-corrosion additives to improve the stability and high oxidation resistance of the oil. 3. Fully synthetic oil: Fully synthetic oil is the best among the three types of oil in terms of quality and durability, and it is also the most expensive type. Generally, it can be used for 10,000-12,000 kilometers in cars without deterioration. 4. The harm of water in oil: If a small amount of water enters the engine and mixes with the oil, the oil quality will deteriorate. Oil containing water will increase the wear of engine components, and may lead to increased engine noise and vibration during future vehicle operation.

[LeCharles]

I remember using 10W-40 oil for my car in the winter two years ago, and it was particularly difficult to start on mornings when the temperature was below minus ten degrees Celsius. The engine would whine for a long time before finally igniting. At the time, I asked a mechanic, and he said that the 'W' stands for Winter, with 10W indicating that the oil can start the engine at around minus 25 degrees Celsius. However, the '40' means the oil is thicker at high temperatures, making it harder to flow during cold winter starts, which can increase engine wear. So now, when I'm in colder regions or temperatures below minus 15 degrees Celsius, I switch to 5W-30 or 0W-40 oil, as they have better low-temperature fluidity. If your car's manual says 10W-40 is acceptable, it's perfectly fine in southern or mild winter regions, especially if temperatures stay above freezing. But remember, oil aging also affects performance, so it's generally recommended to check it every 5,000 kilometers or every six months—don't wait until problems arise.

[MilesDella]

As someone who frequently tinkers with cars, I'd say 10W-40 oil is generally usable in most winter conditions, but the key factor is the actual temperature. The 'W' stands for winter performance capability - 10W can function at -25°C, while the '40' indicates high-temperature viscosity suitable for daily driving. In southern cities where winter temperatures rarely drop below -15°C, it provides smooth starts and engine protection. However, in northern regions with frequent -20°C conditions, the thicker oil may cause slower starts and increased battery strain. I recommend first checking your vehicle's manual recommendations - many manufacturers specify 5W-30 or similar lower-viscosity oils to optimize winter performance. Oil selection directly impacts engine longevity; for instance, lower-viscosity oils reduce wear during prolonged cold-weather operation under heavy loads while improving fuel efficiency. During routine maintenance, always test the oil's fluidity and never overlook temperature variation effects.

[EmeryDella]

I grew up in the north where winter temperatures often drop to -20°C. 10W-40 oil really doesn't perform well in such conditions. Once my car wouldn't start in the morning, and after struggling for a long time, I finally got it running. When I changed the oil later, I found it had become too thick and clogged. The mechanic told me that 10W oil's minimum starting temperature isn't low enough, and in cold regions, it can easily form sludge, affecting engine start-up. It's best to choose 0W or 5W oil, as they have better low-temperature fluidity and make winter starts much easier. If your winters aren't too cold—say, above -10°C—using 10W-40 is fine and economical. But in frigid zones, don't take risks to avoid putting extra strain on your engine. Also, oil quality matters; don't skimp by using inferior products. Regular oil changes will keep your engine safe.