Should You Warm Up the Car Before Changing the Engine Oil?

[StHarrison]

You should warm up the car before changing the engine oil. Steps for changing the engine oil: 1. Start the car engine to allow the oil to flow fully within the engine and carry away impurities; 2. Lift the vehicle using a car lift; 3. Unscrew the oil pan bolt and open the oil filter; 4. After all the oil has drained completely, install the new oil filter and then pour in the new oil. Engine oil serves to lubricate and reduce friction, assist in cooling, seal against leaks, prevent rust and corrosion, and provide shock absorption. Engine oil consists of two parts: base oil and additives. The base oil is the main component of the lubricant, while the additives compensate for and improve any deficiencies in the performance of the base oil.

[ODallas]

Before changing the engine oil, I highly recommend warming up the car first! After starting the engine, wait for about five to ten minutes until the temperature gauge needle reaches the middle position. Warming up the car makes the old oil thinner, just like melted chocolate, so when you unscrew the drain plug, the oil can flow out faster and more completely. If you change the oil when the engine is cold, the old oil will stick stubbornly in the corners of the engine, and the new oil might get contaminated by the leftover dirty oil. However, remember not to rush into the job right after warming up—wait for about ten minutes after turning off the engine. Otherwise, the scalding hot oil could splash out and burn your hands. Last time I changed the oil myself following this procedure, I drained nearly 5 liters of old oil into the drain pan, which was about half a bottle more than when I did it with a cold engine.

[KaiAnn]

As a frequent car maintenance user, I believe warming up the engine depends entirely on the situation. If it's just an oil change, warming up the engine can indeed help drain the old oil more thoroughly. However, pay attention to the temperature—during a midday oil change in summer, the engine is already hot, and idling to warm it up further can easily cause the oil temperature to become too high. In practice, I focus more on the draining time: when the engine is cold, you need to wait at least 20 minutes for the oil to fully drain, whereas after warming up, it flows smoothly in just seven or eight minutes. Another detail is the oil filter—it's easier to unscrew when the engine is warm, unlike when it's cold, which can be a pain. However, if you're using full synthetic oil, the difference between cold and warm engines isn’t significant, as its cleaning performance is strong. Remember, whether you warm up the engine or not, always park on level ground to avoid spilling oil everywhere.

[MaximusAnn]

Just saw this technical question and found it quite interesting. Actually, the principle of warming up the car is simple: cold engine oil has high viscosity and poor fluidity, while hot engine oil has low viscosity and flows quickly like water. Therefore, after warming up the car, when you remove the oil pan drain plug, over 90% of the old oil can be drained, whereas with a cold engine, at most 70% can be drained. My usual practice is to start the vehicle and drive it for about three kilometers to allow the coolant to circulate normally to every component. After turning off the engine, don’t start working immediately; wait for ten minutes to let the temperature drop below 60 degrees, then wear thick gloves before removing the drain plug. Pay special attention to some car models with design issues, such as older cars with irregularly shaped oil pans that can accumulate more sludge when cold. Overall, changing oil after warming up the car has more advantages than disadvantages, but remember not to perform this operation on a slope.

[EliLee]

I have personal experience with this. Last month, I went to my friend's auto shop to change the oil, and he insisted that doing it on a cold engine was more convenient. As a result, the oil drained extremely slowly, and we even had to use an air pump to blow air into the filler port to fully drain it. The next day, I changed the oil myself after warming up the engine, and the difference was night and day: the old oil gushed out like a floodgate opening, draining completely in just ten minutes, with even the oil pan screw getting less dirty. Later, I looked it up and learned that when the engine is warm, metal components expand, creating larger gaps for faster oil drainage. Of course, there are downsides to working on a warm engine, like having to suit up in long sleeves to avoid getting burned by splashes. Overall, I still recommend working on a warm engine, especially during winter.

[VanLydia]

I've followed discussions on foreign forums about this, and the conclusion is clear: 90% of technicians support changing oil when the engine is warm. When the engine is warm, oil flows back from the top of the engine to the oil pan, creating greater drainage pressure. I have a practical tip: start the car and drive until the coolant temperature reaches around 90°C (needle in the middle), then turn off the engine and wait exactly eight minutes. At this point, the oil temperature is just right—between 50-60°C—providing good fluidity without being scalding hot. Additionally, changing oil while the engine is warm is particularly effective for removing carbon deposits, as high temperatures help soften and flush out deposits. However, be mindful of certain Japanese car models with oil pan designs where the drain port is positioned lower—prepare an oil catch pan for warm oil changes. Lastly, never warm up the engine in an enclosed garage to avoid carbon monoxide poisoning.