Can You Add Oil to a Hot Engine? (Explained)

Proper management of the oil level of a car is very important as it ensures the car works without problems. But when can oil be added to an engine? Can you add oil to a hot engine?

This article aims to direct vehicle owners on how to add oil to their vehicles when to do it, and lots more. Reading this article will also teach you how to properly maintain a car.

A very popular belief is that if you add oil to a hot engine, it causes cracks. This belief is based on how metal shrinks and expands as temperature increases and decreases.

When it happens fast, sudden deformation capable of breaking the material may occur. A good example is how glass breaks off when boiling water is poured into it.

Although, no real hazard exists in putting oil in an engine that is hot because the metal parts of the engine are not so fragile and are flexible only to an extent.

Moreover, engine oil absorbs heat slowly compared to water, and it does not have a fast cooling effect like water.

There is a need to wait for a while before checking the oil level because the oil goes back to the drain when the vehicle is turned off. During this period, the engine cools off, and the heat reduces even more when adding oil.

When putting more oil in an engine, it should be done using a method that ensures overfilling does not occur.

A very simple way to do this is by observing the quantity of oil required to be added, using the MIN and MAX signs as a guide. Most times, the only difference between these two signs is one quart.

So, add engine oil with about 0.125 quarts before rechecking the level till it gets close to the maximum.

Also Read: How Much Oil Does My Car Need?

Is It Better to Add Oil to a Hot or Cold Engine?

Doing any of these is not advisable as there will be difficulty in knowing the correct oil level when reading the dipstick.

This is because the oil usually gathers at the base of the engine in the oil pump if the engine is cold, while for hot engines, the oil circulates the entire engine, and you won’t get the correct oil level if you check with the dipstick.

The best time to check and add oil to an engine is when the engine is slightly hot, but you have to allow the cool down for about 5-15min.

While waiting, the oil goes down and gathers in the oil sump, which improves the accuracy when checking with the dipstick.

There is the need to get the engine heated first, then read the oil level after two to five minutes for cold engines.

While the engine is running, adding oil to the vehicle is possible. The entire process is based on the quantity of oil being added and not when the oil is added.

What Happens if You Add Oil While the Engine Is Still Hot?

The worst that could happen if oil is added when an engine is very hot is that it might cause smoke in the engine or make the engine go up in flames.

Accidents from oil burns are quite terrible because the oil becomes very hot. Therefore, it is advisable to wait for about 30 minutes so the engine oil may become cool enough to allow changing oil easily.

Many vehicle experts believe it is better to put oil in a vehicle when the engine is warm. However, if the engine has already cooled off and has stopped running for a while, the oil can be added freely without any worry.

How Long for the Engine to Cool?

If you’re just adding oil to the engine, there is no need to wait for the engine to cool down before adding oil.

But, if it is to change the engine oil, it is important to wait about two hours to allow the oil to cool down before changing it. Removing oil is quite different from adding oil.

The engine needs to cool down before changing the oil. So that when the engine oil is drained, it will not be too hot.

If the engine becomes cool, other vehicle parts also get cool. Hence, getting hurt from the engine’s heat may be avoided, making the changing process hazard-free.

Also Read: How Long Does It Take for a Car to Cool Down?

What Is the Ideal Temperature to Add Oil?

You can add oil to a hot, warm, or cold engine. This is because only minor differences exist between these conditions. Although, making sure the vehicle is neither too cold nor too hot is advised.

If a vehicle has been exposed to weather less than zero degrees Celsius and has been there for a while, oil should not be added at such a temperature.

For this scenario, starting the vehicle to warm up the engine for a short time before adding oil is recommended.

Can You Add Cold Oil to a Hot Engine? (Detailed Answer)

Yes, you can add oil to a hot engine. The temperature of an engine does not matter when adding oil. It is important to note that the engine’s temperature cannot be judged by outer parts of the vehicle that may be extreme.

If oil is being added to a very hot engine, it can cause smoke in the engine, or it may lead to the engine going up in flames.

Therefore, many car experts agree that it is better if oil is added to an engine when it is warm. However, oil can also be added to an engine that has cooled already.

Upon checking the vehicle’s oil level, allowing the engine to cool for about 5 – 10 minutes is very important as this prevents getting burnt or injured during the process.

Not to forget that the type of oil used can also influence the reading when checking the oil level in the vehicle. Just a few regular oils do not increase and then decrease averagely.

This does not affect the engine or the outer temperature, and a few synthetic oils contract when the outer temperature is cold. Also, it expands when the temperature outside is hot.

Furthermore, several modern vehicles are made with electronic gauge controllers. These controllers automatically gauge the oil level in the vehicle.

Also Read: Oil on Spark Plug Threads (Causes & Solutions)

How to Check a Car’s Oil Level

It is important to check if oil is needed in a vehicle by using dipsticks that have a MIN and MAX sign.

Several cars have dipsticks, which makes the process easy, but some cars are made with sensors, which are not the best as they break easily.

In using dipsticks to confirm accurate readings, the oil level should not be far from the MAX level or somewhere between both signs.

Using the dipstick appropriately can be achieved by following the steps below:

1. Switch off the car engine. Ensure the hands are not close to the vehicle’s cooling fan as it can work automatically even when the engine is off.
2.  Wipe the metal part of the dipstick with a clean fabric.
3. Put the oil dipstick back in the engine.
4. Remove the dipstick for a second time and check the oil level.

If the level is anywhere between MIN and MAX, there is no need to add oil to the vehicle. However, if seen to be at MIN or below, there is the need to put more oil in the vehicle.

Check again: The above procedure should be repeated to double-check the precise level of engine oil.

How to Add Engine Oil to Your Car

Oil should be added as soon as the dipstick indicates a severely low oil level.

Firstly, ensure that suitable oil is chosen for the vehicle. It is usually specified in the owner’s manual.

• To determine the quantity of oil to be added, gauge oil level using the oil dipstick.
• Open and take out the tank cap where the oil is stored.
• Then, add a small quantity of new engine oil; using a long-neck funnel is highly recommended, then wait for one or two minutes to enable the oil to flow to the oil tank.
• Use the dipstick to gauge the oil level and add little oil until it is enough.

Note: Putting excess or inadequate oil will consequently affect the engine. Therefore, adding oil to the full line is usually not recommended. However, filling oil to a point before the full line is ideal.

Check out this video for more tips on how to add oil to a car

Should You Add or Change Oil?

It is important that a vehicle is serviced regularly, as recommended by the car manufacturer.

When it is discovered through the dipstick that oil levels are low, the engine oil needs to be topped up if the oil loss is not a result of a leak or any other problem.

A small quantity of oil may be used while driving a vehicle, but an excess loss of oil might be a warning sign of a more serious issue.

A useful general principle is that after every thousand miles covered, if the oil level goes below one quarter, then it is possible that leakage might cause such loss.

Why and When Does Your Car Need Oil?

Oil is important in making a vehicle run smoothly, as it plays the role of a lubricant in the engine.

The car’s engine comprises several metal parts that make contact with each other every time the vehicle is being driven; these metal parts will become worn and broken very quickly if not properly lubricated.

A way to minimize damaging these parts is by warming up the vehicle for about 1 minute before changing the gear to drive, allowing oil to move around the engine.

Besides working as a lubricant for the several contacting parts of the vehicle’s engine, it also prevents the engine from getting too hot. It also takes away small dirt and particles found in several narrow corners.

Also Read: Oil Smells Like Gas (Causes & Solutions)

Conclusion – Can You Add Oil to a Hot Engine?

Putting oil in an engine can be done anytime regardless of the engine’s temperature, although adding oil to an engine when it is warm is the best time.

Use the dipstick to gauge oil levels and top up the oil little by little, not just at once.

Overfilling the engine will cause serious problems, and the engine lubrication will be negatively affected. However, if the filling is done with patience, the possibility of overfilling the engine will be reduced.