At What Temperature Does Engine Oil Freeze?
3 Answers
The freezing point of engine oil depends on its type: 1. 5W oil can be used at temperatures as low as -30 degrees Celsius; 2. 10W oil can be used at temperatures as low as -25 degrees Celsius; 3. 15W oil can be used at temperatures as low as -20 degrees Celsius; 4. 20W oil can be used at temperatures as low as -15 degrees Celsius. The functions of engine oil are: 1. To separate the surfaces of relatively sliding parts, thereby reducing wear; 2. To bring heat back to the oil tank and then dissipate it into the air, helping the radiator cool the engine; 3. To circulate carbon deposits, sludge, and worn metal particles from engine parts back to the oil tank, washing away dirt generated on the working surfaces of parts through the flow of lubricating oil.
I've been driving for decades, often taking long trips in the north. Engine oil can indeed solidify or thicken in sub-zero temperatures, affecting engine startup. The specific temperature depends on the oil type: conventional mineral oil may stop flowing around -20°C. I once encountered -25°C where the oil in an old car was like frozen grease, making it impossible to start. Switching to synthetic oils like 0W-20 or 5W-30 made a big difference, with pour points as low as -40°C and maintained strong lubricity. When choosing winter oil, pay attention to the W value in the SAE grade - the smaller the number before W, the better the cold resistance. Using the wrong oil can increase fuel consumption or even damage the engine. I recommend drivers in cold regions prioritize synthetic multi-grade oils and check oil quality seasonally to avoid surprises.
After working in the auto repair shop for so many years, I've seen plenty of issues with engine oil in cold weather. Oil doesn't actually freeze, but its viscosity increases significantly at low temperatures, which is called the pour point. Different oils have pour points ranging from -20°C to -60°C: conventional oil may thicken at -20°C, while 5W synthetic oil often remains fluid at -30°C. If the temperature is too low, the oil pump can't draw the oil properly, leading to difficult cold starts and increased wear. I've repaired many winter engine failures caused by using expired or mismatched oil. When choosing oil, check the W rating, and change it regularly to ensure the additives remain effective, especially in cold regions. A simple oil change can protect your car and extend its lifespan.
