Should Engine Oil Be Checked When the Engine is Cold or Hot?
2 Answers
Check the engine oil when the engine is cold. The oil level should be between the upper and lower marks on the dipstick, which indicates a normal oil level. Alternatively, you can turn off the engine after driving and wait for about 15 minutes before checking the oil level to ensure accuracy. This waiting period allows the oil inside the engine to flow back into the oil pan for a proper measurement. The steps to check the engine oil are as follows: 1. Locate the dipstick handle in the engine compartment and prepare a piece of paper towel; 2. Pull out the dipstick and use the paper towel to completely wipe off the oil from the dipstick head; 3. Reinsert the cleaned dipstick and then pull it out again. The oil adhering to the end of the dipstick can now be observed for measurement.
Generally speaking, I recommend checking the engine oil when the car is cold for the most accurate and reliable results. When my own car is parked on level ground with the engine completely cooled down, such as after overnight parking or sitting for several hours, the oil level shows steadily within the normal range on the dipstick. This is because when the engine is running at high temperatures, the oil expands and spreads out. Checking immediately after driving can lead to underestimation and potential misjudgment, and may also cause oil splashing onto your hands. When the car is cold, the oil settles back to its correct position. I do this every week: pull out the dipstick, wipe it clean, reinsert it, then remove it to check, ensuring the level is between the high and low marks. This helps detect low oil levels early, preventing engine wear or failure. Maintaining this habit long-term keeps the car running smoothly and saves on repair costs.
