Maintaining your car’s oil level and regularly changing it is essential to keeping your vehicle running smoothly for as long as possible. But should you add oil to your car when the engine is hot or cold? How does your engine temperature affect your car’s oil?
You can put oil in your car when the engine is hot. Check the oil level after the engine has cooled, but it is safe to add oil to your car if it is warm or slightly hot, provided it has been turned off for several minutes. Be sure to avoid overfilling the oil past the “max” line on the dipstick.
To learn more about checking, changing, or adding oil to your car and if your engine should be hot or cold while doing so, keep reading. We’ll cover everything you need to know.
Should Your Engine Be Cool Before Adding Oil?
When performing a simple top-up to your engine’s oil, for most cars, it doesn’t matter much if the engine is warm, cold, or in between, as long as the temperature isn’t too extreme in either direction.
A scorching hot engine can cause smoking or a fire if you spill any oil onto it during the top-up.
While most car experts agree it is preferable to add oil to a warm engine, you can also add it if the engine has cooled down.
However, when checking your car’s oil level, it is best to wait until the engine has cooled off for at least 5 to 10 minutes to avoid burning yourself with the hot oil already in the car or on and around the dipstick.
Keep in mind that the type of oil your car uses can affect the reading when you check your vehicle’s oil level beforehand.
While most regular oils tend to expand and contract at a normal rate regardless of the engine or external temperature, some synthetic oils will contract when it is colder outside and expand during the warmer months and give inaccurate readings.
Additionally, many modern cars have electronic level controllers that will automatically measure your oil level when the vehicle is on level ground.
With these types of cars, it is best to check the oil while the engine is warm.
As long as the temperature outside isn’t very cold or near freezing and your car has been turned off for several minutes, it is safe to check or add oil regardless of internal or external temperature. Just be careful as you do, because the engine is hot enough to burn your skin.
Can You Add Oil Instead of Changing It?
It is crucial to get regular oil changes as directed by your car’s manufacturer.
However, you may sometimes need to add a small amount of oil to your vehicle if you notice the levels are a bit low according to your dipstick, as long as a leak or a more serious issue is not causing your car to lose oil rapidly.
It is normal for a small amount of oil to burn off as you drive your car regularly, but excessive oil loss is often problematic. A good rule of thumb to remember is if your oil level is one quart low for every 1,000 miles (1,609.34 km), a leak might be to blame.
How to Check Your Car’s Oil Level
To determine if your car needs more oil, it is best to first check the reading on your car’s dipstick. The dipstick will have a “min” and a “max” line, and your oil level should be somewhere between the two and as close to the “max” line as possible without overfilling.
Of course, if your car is older and doesn’t have a dipstick or a dipstick holder, you may want to ask a mechanic how to proceed.
Checking your car’s oil level is quite simple and should be done when your engine has cooled off. It is best to perform a check around once per month for good measure, even if you’ve recently gotten an oil change.
Just follow these simple steps:
- Make sure your car is parked on level ground and turned off. It is best to let the engine rest and cool for several minutes before checking the levels.
- Open your vehicle’s hood and locate the dipstick. Usually, it will have a brightly colored red or orange tab on the end of it to help it stick out even to a beginner.
- Pull out the dipstick. Make sure you wipe it clean with a dry cloth before re-inserting it, as the initial reading will likely be incorrect thanks to oil splashing around and staining the dipstick.
- Put the dipstick back in and wait a few seconds before removing it again. The dipstick will now give you an accurate reading of your vehicle’s oil level. As we touched on earlier, it should be somewhere between the minimum and max fill lines and as close to the max line as possible without overfilling.
If your oil level is normal, then great! You don’t need to do anything else.
If it’s a bit low, you can add a small amount, wait for your engine to absorb it, and check the level once more. Again, it doesn’t matter much if the engine is warm or cool, as long as it isn’t extremely hot or cold.
Keep repeating this process until the oil level is within a normal range. Be sure to get regular oil changes often, as your car can’t rely on top-ups alone. Old oil will mix with the new and develop a watery consistency over time, and the thin, runny oil won’t be able to lubricate your engine effectively.
Why and When Your Car Needs Oil
Oil is vital to keeping your car running correctly, as it acts as a lubricant inside your engine.
Your car’s engine has lots of metal parts grinding against each other every time you take your car out for a drive, and if these parts are not well lubricated, they will wear against each other and become damaged very quickly.
One way to mitigate damage to these metal parts is to let your car warm up for about a minute or so before putting it into drive to let the oil circulate through the engine.
In addition to serving as a lubricant for your engine’s hundreds of interacting parts, it also helps prevent your engine from overheating and eliminates tiny deposits of dirt and debris that collect in its many narrow crevices.
Overall, it is safe to add oil to your car if the engine is warm, but it is best to check your oil levels after your car has cooled down a bit. If the motor is too hot, it can be dangerous to add oil, as you can burn yourself or drip oil onto the engine, causing it to smoke or start a fire.
Check your car’s oil levels monthly and get regular oil changes to keep everything running smoothly, and always turn the engine off and let it rest for a few minutes before opening the hood.
Related: High-Mileage vs. Full Synthetic Oil: What’s the Difference?