Certainly, you’ll agree with me that changing your oil regularly is one of the essential maintenance you need to perform for your car. The engine needs the oil to function smoothly and properly. Apart from that, oil also helps to prevent the engine from overheating; it does that by lubricating all the moving parts.
When it comes to changing the engine oil, one of the few questions that people often ask is – how ideal is it to put oil in a hot engine?
You can always add oil to a hot engine. However, you need to know that it isn’t the best option. According to the National Automotive Parts Association, the best time to put oil is when the engine is cool. But if you have to do it when the engine is hot, you need to ensure that the oil isn’t underfilled or overfilled.
Is it even ideal to add oil to a running engine? Does it matter if I let my car cool down before adding oil? How long should I keep my engine cool before adding oil? In the rest of this article, you’ll find answers to these questions and more.
Can You Add Oil to a Running Engine?
Let’s start with the first burning question; is it a good idea to add oil to a running engine?
The simple and short answer to the question is no, it’s not the best idea to add oil while your car engine is running.
In the case where you find yourself in the middle of the road and notice the oil low-level warning sign on your vehicle’s dashboard, the first thing is to stop the car. After that, you need to wait for a while before trying to add oil to the engine. According to the National Automotive Parts Association, the best time to drain your oil is when the engine is hot, while the best time to introduce new oil to the tank is when the engine is cool.
With your car running, the engine will inevitably become scalding hot. There are a few reasons why you shouldn’t add oil during this period – when the engine is extremely hot. Let’s have a quick look at them below:
- Oil Level
One of the reasons why it isn’t ideal to add cold oil to a running engine is that this option makes it a lot more difficult to know the required oil level. How exactly do I mean? It’s pretty simple; when you add oil to a cool engine, it’ll become very easy and quick for you to determine whether it’s underfilled, overfilled, or exactly at the required level.
A running engine is extremely hot. So, when oil comes in contact with it, it’ll become very light and thin. That’s not all; the engine oil will also become useless at the time, as it’ll possess poor lubrication and viscosity that’s close to that of water.
- Possibility of Cracks
Another reason (the least important) why it’s not advisable to add oil to a running engine is to prevent cracks. According to the general belief, when cold oil is added to a very hot component, it could result in cracks. This belief is based on the theory that metals tend to shrink or expand depending on the temperature changes. But this, in many cases, doesn’t happen. Matter of fact, it only occurs in the worst-case scenario.
While it’s not the best idea to add cold oil to an extremely hot engine, you can always wait for it to cool down to some extent before trying to introduce it.
Should I Let My Car Cool Down Before Adding Oil?
We are still using the same scenario – finding yourself in the middle of the road and noticing the oil low-level warning sign on your vehicle’s dashboard.
Now that you understand that it isn’t a very good idea to add oil to your car engine when it’s running, the next question is should you let the car cool down before trying to introduce the new engine oil?
Let me start by saying that you don’t necessarily have to cool down your engine to add oil. But yes, for a couple of reasons, letting your car engine cool down after running for some time is the best option.
With this option, it becomes much easier for you to keep track of the oil level inside the tank. In case you don’t know, you need to have the correct oil level in your car. This way, you’ll be able to prevent a couple of problems. For instance, if the engine is overfilled with oil, it will most likely cause the crankshaft to be in contact with the oil, resulting in aeration. The aftermath of that is; you’ll have a foamy and frothy oil, which won’t be able to lubricate the moving parts of your engine.
Another thing you need to understand is that the oil tends to settle down in the tank pan when the engine is cool and not running.
So, with the engine cool before adding oil – it won’t only allow you to determine the oil level accurately but will also allow the oil to settle well inside the oil pan.
How Long Should You Let the Engine Cool Before Adding Oil?
As earlier mentioned, the best thing you can do, in the case where you need to add oil to the oil pan in the middle of the road, is to stop for a little while and allow the engine to cool down. But here’s a quick question, how long should you let the engine cool before adding oil?
To answer the question, I’ll say 20 to 30 minutes is enough time to keep your engine cool. At this point, your engine will be warm below 100 degrees and safer for you to monitor the level of oil in the pan.
