Quiz time! What is one of the most important things you can do for your vehicle today? That’s right, you should check the oil level. Knowing when you need to change the oil or top it off before a long drive is essential to preserving the life of your vehicle. However, you also need to know how to check the oil correctly. That means knowing how long to let your engine cool before checking the oil. Do it wrong, and you could get an incorrect reading.
Measuring the oil level is easy, but you could also make an easy mistake. That’s why we’re going to review the steps, so you can do it right every single time. Let’s begin.
**Note** – A quick hello to anyone reading this, I’m Alastair and this is my site Synthetic oil.me. I started this site to help people with their oil questions, and hopefully what you’re about to read will help answer your questions. This page may include affiliate links to the likes of Amazon, which if you make a purchase I qualify to earn a (typically small) commission. Don’t worry as this won’t cost you anything, the likes of Amazon pay any commissions. Thank you in advance for your support as this helps bring you more (hopefully) helpful content.
What is Motor Oil?
First off, motor oil. What is it and why do you need to check it regularly? Motor oil, particularly synthetic oil, is a mix of oils and additives that are used to lubricate the engine of the vehicle. The additives also clean, cool, reduce friction, and extend the overall lifespan of the engine. Modern synthetic oils are going above and beyond these jobs and can also remove dirt and grime from the engine and increase overall efficiency (while reducing emissions).
Keeping your engine oil clean is important. Every time there is combustion in the engine, there is a chance for contaminants to get into the oil. When those contaminants settle, the sludge builds up and can move around essential parts. If you use the wrong kind of oil, choose a poor quality oil, or even simply forget to check and clean the oil, you are damaging the engine.
Dirty or low oil also diminishes the efficiency at which the vehicle operates. So if you notice that your car is lagging or that the fuel economy has suddenly gotten worse, you may want to check the oil in your car ASAP.
Should I Check My Oil When The Engine is Hot or Cold?
The best time to check the engine oil level is when the motor is either slightly warm or cooled. If your car has recently been run, turn it off and wait for everything to cool down for about 10-15 minutes. After 15 minutes, the oil will have descended into the oil pan, making it more accurate to check the level.
That said, checking the engine oil level when it is cold is the best. Since motor oil can reach 250 degrees F (210 degrees C), you don’t want to get any on your hands shortly after running the vehicle. Secondly, if you check the oil while the engine is recently run, you are going to get an incorrect reading. The oil will still be around the engine, pistons, etc. which means it won’t be all in the oil pan. If you check at this stage you will end up overfilling the oil reservoir, and that can cause an oil leak or cause engine damage.
On the other hand, if it’s too cold outside? Fire up the engine for a few minutes. Let the oil circulate and get a little warm. Then shut the car off again, wait 5-10 minutes for the oil to settle, and then take your reading. This is only necessary for the colder environments, due to oil being denser when cold, dropping the level on the oil dipstick.
How Long Should I Let The Engine Cool Before Checking Oil?
If you want to check the oil level in your car after it has been running, it is safest to wait a couple of minutes at least. There are different opinions on the internet, but the consensus is between 5-10 minutes after running. Sometimes, 1-2 minutes of cooling is enough, depending on the temperature of the engine. Within 5 minutes, the heat in the engine begins to dissipate and the oil starts returning to the oil pan. Personally, if you’ve been on a long journey it’s best to wait around 15 minutes (maybe even 20).
When it’s very cold out, don’t wait too long, but don’t check the engine as soon as you shut it off either. Doing so could result in an inaccurate reading.
A Note on Oil Expansion
The kind of engine oil you use will change how much the oil expands when hot. Synthetic oil, for example, has the greatest rate of contraction and expansion. During colder temperatures, synthetic oil becomes more viscous. When hot, it runs more fluidly through the engine.
Conventional oil is much less affected by temperature fluctuations. If you are checking the level of regular oil, the difference between hot and cold reads will be minimal.
Some newer car models have an electronic oil level controller installed. These controllers will only measure the level of the oil when the temperature has cooled and the car is parked on a flat surface. If your car has one of these sensors, it is best to check before the oil has cooled completely.
Is It OK to Check Oil While The Engine is Hot?
There is no best temperature at which to check the oil in the engine. You have to take into account the type of vehicle, the outside temperature, and the kind of oil used. That said, for most reasons, you can check the oil if it is hot or cold, and you will get around the same reading each time. Hot or warm engine oil is going to provide an accurate reading.
A car does not have to sit for a long period in order for you to check the oil level. Let the vehicle sit for about 5-15 minutes.
How to Check Engine Oil
Now that you know that checking your engine oil can be done either hot or cold, let’s talk about the best way to go about checking. Most often, new car owners get confused during the basic steps. Here is how to check the motor oil:
First, make sure that your car is parked on flat ground. If the ground is uneven, the reading will most likely be inaccurate.
If you are inexperienced with checking the motor oil level, only check the oil when the car has had a chance to cool. The hot engine could scald you if you’re not careful. Should the outside temperature be around or below freezing, warm the engine slightly. Once the engine has been warmed, let the vehicle sit for 10-15 minutes before measuring the oil.
From there, locate the dipstick. You will find it in the engine bay. Remove the stick. Take a clean towel or rag and wipe the dipstick. Note the color of the oil on the dipstick. Next, dip the stick once again into the oil reservoir, making sure it’s fully pressed into position, the last little bit may have some resistance. Next pull the oil dipstick free. The level of the oil will be displayed on the stick, between the minimum and maximum lines printed on the dipstick. If the oil is lower than the minimum, you will need to add more oil.
Many new car models may have an electronically controlled oil level sensor, so check your owner manual for the best method.
Although there are different perspectives about how cool an engine has to be when checking the oil, it is agreed that waiting 10-15 minutes after the car has been warmed is the best time to check the oil level. You can also measure the oil when cold, but you should not do this when the outside temperature is close to freezing. As long as you check the oil level on a flat surface while it is still a little warm, you should be able to get an accurate reading.
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