Is It OK to Slightly Overfill Engine Oil? (Explained!)

The engine oil is one of the crucial components of every car. Thus, it’s one of the things most drivers pay attention to. Since it’s one of the things they check most, it’s also one thing that usually goes wrong. One common mistake would be overfilling it. Thus, you may ask:

Is it OK to slightly overfill engine oil? In general, it’s OK to run an engine filled with half a quart to a quart overfilled. However, if you fill more than such an amount, you’ll get worse gas mileage. It’s because the oil would harm the crankshaft, resulting in a damaged engine. Thus, you need to be cautious when dealing with such.

If you’re new to this kind of thing, it may seem overwhelming to avoid such an error. Still, it’s one of the things you’ll get the hang of as you continue. This article will give you everything you need to know about this matter.

Without further ado, let’s get into it!

Is It OK to Slightly Overfill Engine Oil

What Happens If You Slightly Overfill Engine Oil?

Though it’s not a good thing, it won’t cause any issue if you slightly overfill your engine oil. However, it only goes as far as you only overfilled by half a quart to a quart.

The oil chambers in vehicles have a specific allowance for these kinds of errors. Still, you need to keep in mind that there’s a reason the limits exist.

If the engine receives too much oil, the oil pan’s fluid level will be so high. It can come to the extent of splashing some of the moving parts in the engine block.

As a result, it can whip the oil into a frothy consistency. Such a problem would end up damaging your engine, especially in the long run.

Now, if it’s only a slight overfilled, then it shouldn’t cause any issue. Still, it would be best to be careful and avoid doing it again.

With this in mind, you may be curious to know the extent of overfilling it.

Related: Overfilling Engine Oil by 1/2 Quart or 1 Quart

How Much Oil Overfill Is Too Much?

While a slight overfill shouldn’t cause concern, there’s still a limit to how much your car engine can take.

Such a limit varies on the type of car and the size of the oil chamber. However, take it as a rule of thumb that a millimeter or two above the fill line remains safe.

In short, a quart or more of extra oil in the engine should be a sign for you to do something.

Now, how would you know if you overfilled your car’s engine with oil, you might ask.

How Do I Know If I Put Too Much Oil in My Car?

As I said earlier, a bit of excess shouldn’t cause an issue. It means that a millimeter or two above the line should be alright.

However, a quart or more of extra oil is something that can harm your engine. You can tell such a thing by measuring the oil through the dipstick.

Now, if you’re already hitting the road, you can tell you overfilled the oil through the following:

  • The engine becomes noisier than usual.
  • It’s becoming difficult to speed the engine up.
  • The engine starts to stall or misfire.
  • The engine can’t start.
  • The car temperature starts to rise.

If ever you encounter such problems, you may want to stop and check it out. Some car mechanics usually suggest that you siphon the excess oil from the dipstick or crankcase cap.

overfilling motor oil

How Do I Remove Excess Oil From My Car?

If you overdid the oil and filled it with more than the necessary amount, you can use these two ways to remove the excess:

Do the oil-plug method:

If you poured too much oil, the best way to remove such is to drain it from under the car. In short, you need the drain pan and the socket wrench.

Here are the steps you can follow:

  • Crawl under the car and locate the oil plug.
  • Put the drain pan under the oil plug. This way, it can collect the drained oil.
  • Use a socket wrench to loosen up the oil plug. You must do it slowly. Doing otherwise can cause the plug to come out, wasting all the oil of your engine.
  • If you do it slowly, it will allow small oil leakage.
  • With a dipstick, continue measuring until it reaches an average level.
  • Tighten the plug once you reached the average level.

Aside from the oil-plug method, you can also use a suction pipe.

Use a suction pipe.

Using a suction pipe is the easiest way to drain oil. If you have one, you can put it on the hole where you put your dipstick.

This way, you can suck the excess oil until it reaches an average level. While this method is quite simple, it can also take quite some time.


Slightly overfilling the car oil can happen all the time. While it’s alright for a small amount, it’s still not a good thing to continue doing.

True enough, the oil chambers can take a millimeter or two of extra oil. Still, it would be best to remain between the measuring lines.

This way, you can maintain the best out of your car and avoid problems or issues related to oil overfilling.



Image credits – Canva

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My name is Hank, and I've been in the automotive industry for 27 years. I've been working in my own auto repair shop for the last 13 years, and now I want to help you here, on my blog. Let me know if you have any questions. Read more