Can You Put Oil In A Hot Engine (And Should You?)

There are many reasons why it's better to let your car's engine cool down before checking the oil level with the dipstick or when draining or changing the oil. Hot synthetic oil could reach over 200 F° and burn your hands and skin. Moreover, letting a hot engine cool down for 5 to 10 minutes allows the recirculating oil to drain inside the sump, allowing for more accurate measurements when checking the oil level.

However, is it safe to put fresh oil into a hot engine? I do it constantly when needed, and the only thing to worry about is dealing with the intense heat inside the engine bay. If you want to add oil when the level is low or after doing some hot laps around the racetrack, it is safe to do so, provided you wear safety gear (some gloves and protective eyewear) and shut off the engine before proceeding.

Unlike opening a radiator cap, where there's a considerable risk of scalding or burning if you attempt to open it while hot, there is no such danger in opening the oil cap of a hot engine, provided you turn off the motor first. If you do so while the engine is running, hot oil could spray everywhere, causing a huge mess and possibly burn injuries.

The best time to drain the oil is when the engine is hot. Oil gets thinner or loses viscosity and drains quicker when hot, leading to more efficient oil changes. Meanwhile, the contaminants trapped in oil are more likely to drain out more effectively at higher temperatures.

If you're planning a DIY oil change in the morning, start the engine and drive around for 15 to 30 minutes, park the car on level ground, shut down the motor, and wait five minutes before draining the oil. The next step is to let the entire thing sit for about 20 to 30 minutes, giving more time for all the oil to drain. The final task is replacing the oil filter, re-installing the oil drain plug, and refilling the engine with fresh oil.

Refer to the owner's manual to know what oil is best for your car and how often it requires oil changes. Meanwhile, take caution when adding oil to avoid overfilling. Always check the oil level using the dipstick before adding oil, whether the engine is hot or cold. Remember to check the oil level at least once a week or before embarking on a long drive to maintain a healthy engine.