Is the correct time to check the oil after the hot car or before the cold car starts?

The oil dipstick must be seen when the car is cold, but I am usually used to checking the oil level when the car is cold the next morning after leaving it overnight. Many car instructions require that the engine be allowed to stand for 10 minutes after the flameout, in order to let most of the oil flow back to the oil pan! Therefore, there is little difference in the amount of oil flowing back to the oil pan after cooling for one night and cooling for 10 minutes. Ten minutes is enough for 95% of the oil to flow back to the oil pan, and it takes a long time for the remaining 1% to flow back to the oil pan drop by drop. Did you all see the oil drain? Usually, most of it is released in less than 10 minutes, but there is still oil dripping down, and it will not be enough until it is completely dripped for half a day! Therefore, there is not much difference between the oil level after flameout 10 minutes and the oil level after standing for one night. 2, 3 mm is the sky-high price!

If you don't turn off the engine, the dipstick will definitely be inaccurate, because there is a lot of engine oil in the pipeline, which will inevitably lead to a drop in the oil level in the oil pan, and most of the engine oil can return to the oil pan after turning off the engine 10 minutes, so the dipstick is inaccurate at this time, but it is practical and reasonable. After standing for one night, more is to measure the amount of oil flowing back to the oil pan (but in fact 100% of the oil still can't flow back after one night, and there must be residues in the pipeline, so we can only observe this thing relatively, not seriously), so the inspection after standing for one night is more accurate, but again, whether it is standing for one night or stopping for ten minutes, the liquid level difference between the two is not big; Even after standing for one night, the oil will not 100% flow back to the oil pan. If measured with a micrometer, the liquid level after standing for three nights is still higher than that after standing for one night, but it has lost its practical significance, so it is enough!