Can Engine Oil Be Ignited by a Lighter?

[JohnLee]

No, engine oil requires a combustible material to ignite. Under normal circumstances, engine oil will not burn when exposed to an open flame without any attached combustible material. However, engine oil itself is flammable, so if there is an attached combustible material carrying an open flame, it can catch fire. Therefore, for safety reasons, it is best to avoid exposing engine oil to open flames. Additionally, storage should be handled with care, and contact between engine oil and open flames should be minimized. The boiling point of engine oil is generally around 150°C, and its flash point should be 20–30°C higher than its operating temperature. The choice of engine oil should be based on the operating temperature, as not all vehicle models operate under the same conditions.

[DelLincoln]

Speaking of whether engine oil can catch fire, I tried it last month when I was repairing my car. At the time, some waste oil had leaked on the workshop floor, and I used a lighter to try igniting it. The flame just produced black smoke and wouldn’t catch fire. The experienced mechanic said this is because fresh engine oil has a very high flash point, and the temperature from a lighter isn’t enough. However, waste oil mixed with gasoline is dangerous. Last week, a trash bin at the neighboring auto repair shop caught fire because of oily rags spontaneously combusting. Remember to properly recycle waste oil and not to carelessly discard oily rags—under the summer sun, they really can ignite! Especially for turbocharged cars leaking oil, deal with it promptly, as engine temperatures can soar past 100°C in minutes.

[DianaRose]

Back when I worked at the tuning shop, the boss always warned us not to smoke near oil drums. Once, a customer didn't believe it and insisted on lighting freshly opened 5W-30 motor oil with a Zippo—the flame licked the oil surface and died out in three seconds. Actually, mineral oil burns easier than full synthetic, but both require over 150°C to ignite. The real flammable one is diesel—last time when we were cleaning a tanker truck, the residual diesel caught fire instantly with a lighter, scaring everyone into grabbing fire extinguishers. Remember to keep oil drums away from welding areas—oxy-fuel welding reaches over 600°C and can definitely ignite them.

[OIker]

Back when I taught chemistry, I demonstrated to students that even at room temperature, pouring out engine oil makes it difficult to ignite with a Bunsen burner. Hydrocarbon substances only become flammable when vaporized, and engine oil's high viscosity makes it less volatile. However, last year, a fire broke out in our residential underground garage, and the investigation revealed it was caused by oil leakage encountering the high temperature of an exhaust pipe. I specifically looked up the data: SN-grade engine oil has a closed-cup flash point of 215°C, while the temperature at the exhaust pipe's front section can reach 500°C. So, don't leave a leaking car parked for too long—oil accumulation on the underbody guard plate is even more dangerous.