There is a lot of debate on whether you should check your car's dipstick when the engine is hot or cold. The main argument for checking it when the engine is cold is that it will give you a more accurate reading of the oil level. When the engine is hot, the oil expands and can give you a false reading of the true oil level. However, some people argue that checking the dipstick when the engine is hot is actually better because it can help you identify potential problems with the oil. If the oil level is low when the engine is hot, it could be a sign that there is a leak or that the oil is burning off too quickly. Checking the dipstick when the engine is cold can also be difficult because the oil can be thick and hard to read. Ultimately, it is up to you to decide when to check your car's dipstick, but doing it when the engine is cold is probably the best way to get a accurate reading.