Filling up the gas tank in your car is something you probably do almost every week. But another item that should be taken care of regularly to ensure your vehicle runs properly is a routine oil change. This ensures that all of the engine parts can operate smoothly and continue to run for many years to come. On modern vehicles, an engine oil light will appear when an oil change is needed and this will be displayed on the front dashboard as an easy reminder.
But what happens when you put too much oil in your car, and will this cause a lot of problems for your vehicle? Let’s take a look at the dangers of overfilling motor oil and what you can do if this happens.
What is Motor Oil?
First of all, let’s start by taking a closer look at motor oil and its importance in the operation of a vehicle. The engine underneath the hood of your car operates with a lot of moving parts. In order to work together and in an efficient manner, they all have to be lubricated properly. This allows there to be smooth operation in the engine and avoids friction build-up which causes heat. This heat is something that you do not want, as it is going to damage the parts in your engine.
So, the job of motor oil is to keep the engine running properly for the duration of your vehicles life. It will circulate through the engine and also has the task of moving dirt and debris to the oil filter. This stops any grime or small metal shavings from moving around in the engine and affecting the vehicle’s performance.
Another reason why motor oil is so essential for your vehicle is that it stops the engine from overheating. With all of those moving parts, the engine needs some help when it comes to staying cool. Less friction between parts means less heat in your engine, and this is exactly what motor oil accomplishes.
For all of these reasons, that is why it is essential to routinely change your motor oil and filter yourself or have it done by a professional. All responsible motorists will know this to be true.
Is It Possible to Use Too Much Motor Oil?
A common question we hear a lot is can you put too much motor oil in your car? The answer to this popular question is of course yes! Sometimes it can be tricky to know the exact amount of motor oil required for your vehicle because all cars are different. But, if you fill it up too much, this is going to be a big problem. The same applies if you use too little motor oil in your vehicle. You have to find out the optimum amount for your car and that information can be found in a few different ways.
If you use too much motor oil, you are going to have a trip to the mechanics on your hands. Now, it is time to discover what will happen if you use too much engine oil.
The Dangers of Overfilling Motor Oil
Poor Engine Wear
The main reason that cars need motor oil is for lubrication which allows all of the engine parts to operate easily. However, if you overfill your car with engine oil, this can actually have the opposite effect. People are surprised to learn that using too much motor oil actually significantly reduces lubrication for the engine parts and can cause them to fall out of time.
How does this happen? Well first off all engines are designed to have a specific amount of oil in them to run properly. If the engine has too little oil or too much oil, problems will begin to be apparent. For instance, too much oil can cause compression and timing issues which can cause your engine to misfire leading to a decrease in horsepower. Too little, and heat will build up leaving you on the side of the road in no time.
Permanent Engine Damage
Of course, bad engine wear is not good, and overfilling your motor oil can actually cause this to happen. We are talking about permanent engine damage. When you have too much motor oil, it can cause too much pressure inside your engine. Some may not think it’s a big deal, but, over time it will cause a lot of damage that is long-lasting or even permanent.
In this scenario, it will not be possible to repair the engine. In fact, you might need to totally replace and purchase a new engine! This is going to cost a lot of money and something you want to avoid at all costs. In this scenario, a lot of people end up giving up on their vehicle and having to purchase a new one. All because they overfilled the motor oil.
Gasket and Seal Failure
So, say you have overfilled your motor oil. The crankshaft of your car is going to whip around this oil. There is going to be air present in the oil and this is going to mean there is a lot of pressure in the system. Gaskets and seals are designed to keep pressures where they need to be and prevent oil from moving to places in the engine that it is not supposed to go. However, they can only deal with the ordinary amount of pressure that they were designed for. When you use too much motor oil these seals and gaskets can be easily compromised and fail leading to a dead engine.
Fouled Spark Plugs
Every combustion engine has spark plugs. Without these little guys, there would be no rumbling of the engine or exhaust coming from the tailpipe. Simply put, no spark, no ignition. Spark plugs are the end current location for your vehicle’s ignition system and if they are not properly kept you’ll be dead in your driveway.
Unfortunately, when you overfill the motor oil in your car, this can lead to your spark plugs being fouled up with all types of grime and gunk. This overflow of excess oil can make its way into the spark plugs and stop them from doing their job. Spark plug fouling can mean that your engine misfires or it does not start at all and you cannot go anywhere.
This is something that you cannot ignore and it will mean that you have to clean them up properly or just replace them. An expense that could have been easily avoided if the right amount of oil had been added to the engine.
Fouled Catalytic Converter
The catalytic converter is an important part of your car. This is the device that controls exhaust emission and in the US this topic part is taken very seriously. The bad news is that when it gets damaged, it is hard to repair. Instead, it is best to replace it completely. But, when this happens, be prepared for a huge bill. We are talking about paying anywhere from $400 to $2,000 just for the parts. This does not include labor costs.
Unfortunately, overfilling the motor oil in your car can lead to a fouled catalytic converter. In extreme scenarios, it is possible that excess oil is going to go down into the exhaust system and into the catalytic converter but I have only heard stories of that actually happening, never witnessed it myself. The more likely cause for overfilled engine oil to damage your catalytic converter is grime build-up due to oil burn-off. Burning engine oil from being overfilled will travel as thick oily smoke which can quickly congest your catalytic converter effectively making it useless. Not only will it stop it from working effectively, but it can actually be very dangerous too. For instance, if the engine oil clogs the catalytic converter this can lead to unhealthy amounts of pollution or even cause a fire underneath your vehicle.
Signs You Have Overfilled the Engine Oil
As you can see, there are a lot of dangers that can occur when you put too much oil in your car. Luckily, there are some simple tell-tale signs that this has happened. These signs should allow you to seek help as soon as possible and try to avoid serious damage to your vehicle. So, here are some signs to look out for and that can indicate you have overfilled the engine oil.
There is White or Blue Smoke
Of course, it is normal to see some exhaust smoke coming from the exhaust pipe when the engine is running. However, if you start to notice that there is white or blue smoke, this is a cause for concern. This could be a result of too much oil in your engine among many other reasons. Spotting this problem is as easy as looking out the side view mirror but my hunch is that you will probably smell it first. Either way, do not ignore this change in engine exhaust production.
You Notice a Burning Smell
A burning smell is never a good sign. This is especially true when you are driving. If you have changed your motor oil recently and then start to smell a burning odor, this could be a sign that you have overfilled it. The oil could have leaked and it may be burning on the engine parts. Thus, is recommended that you stop driving and see what the problem is. If you think that you have overfilled the engine oil, it is time to see a mechanic.
Leaking Oil Under the Car
Sometimes, the signs that you have overfilled your engine oil are obvious. For example, you may notice that there is oil leaking from underneath your car. This can show under the engine and particularly after the car has been parked for a period of time. This can be small drips of oil or it might be larger puddles. Either way, this could be a result of overfilling your engine oil.
The Car Engine is Misfiring
A vehicle misfiring and/or stalling might happen when you overfill the motor oil. The reason for this is because the oil is interfering with the engine’s compression and timing. This is going to be something that can happen all of a sudden and be an easy spot if your engine is acting funny after an oil change. So, hopefully, you can connect these two things and realize that something is wrong.
The Vehicle Will Not Start
There is nothing worse than jumping into your car and realizing that the engine will not start. There can be a myriad of reasons this might happen but putting in too much engine oil can be one of them. Again, this could be a result of fouled spark plugs. They could be coated in engine oil or grime caused by too much oil and this means that they will not ignite the engine. So, this means that when you turn the key, the engine is not going to start.
A Lot of Engine Noise
Everybody knows what a normal car sounds like. If you are driving and start to hear a lot of sounds all of a sudden that you have never heard before, you know that something is not right. This can be a result of too much engine oil and it is a cause for concern. Too much engine oil inside of the engine will cause a lot of turbulence between the moving parts as they struggle to stay in time. This can cause a lot of grinding and screeching noises that will alert you and it can be a sign that you have overfilled the engine oil.
High Oil Pressure Light Turns On
Some vehicles have a high oil pressure light. This is a very important indicator that is going to help you know when something is wrong. In particular, it is going to be a light that turns on when there is too much engine oil. Make sure that you do not ignore this high oil pressure light. It is a signal that there is a problem and it is best to take your vehicle to a mechanic as soon as you can.
Tips to Avoid Overfilling the Motor Oil
Anybody can make a mistake when it comes to too much engine oil. The most important thing is that you learn not to do it again or just do your research before attempting it yourself. We have some tips that can help you avoid overfilling the motor oil in the future.
Know How Much Oil Your Car Takes
To avoid overfilling motor oil, you need to learn how much your vehicle can take. Every car is going to be different and you should not assume that every vehicle is the same. For example, some four-cylinder engines will need around 4.5 liters of oil. If you have an eight-cylinder engine, this can take anywhere from 4.5 to 7.5 liters of motor oil. The simple rule of thumb is the bigger the engine the more oil it will need.
The best thing you can do is check the owner’s manual of your vehicle and if you have misplaced it you can directly call your vehicle’s manufacturer or contact a certified mechanic like me. If you do have your owner’s manual however you can find your oil amounts under the “fluids” or “Routine Maintenance” sections accordingly.
Purchase the Correct Motor Oil
A lot of people take purchasing decisions into their own hands. And unfortunately, some believe that all motor oil is the same and they can buy any product for their vehicle. But, as we have mentioned, the owner’s manual is going to outline the correct engine oil to use for your car. All oil types perform differently from one another and there is a reason why that oil has been chosen by your manufacturer. Pay attention to these details and buy the correct motor oil!
While doing your research you may find that your precise motor oil is offered by many different companies. Some are better than others and we will be ranking them in an upcoming article shortly based on professional opinions so keep your eye out for that. But until then I will admit that usually, the most expensive oil is the best oil and will result in better and more healthy miles for your vehicle.
Check Your Engine Oil Level When the Engine is COLD
A lot of people make the mistake of checking the motor oil when the car has just been running. The best way to get a good reading is to check the oil level first thing before you start the vehicle. When motor oil is warm or hot it will expand and decent amount giving you a bad reading if you are checking the oil level while the engine is warm. You also want to ensure that your vehicle is not on a slope when you check the oil level, flat ground will give you the best reading. These factors will play a part when it comes to getting an accurate reading.
How to Read a Dipstick
When you pop the hood of your vehicle, you will notice the yellow or orange dipstick handle somewhere on the top of your engine. There is often a noticeable loop, as well as a label that could mention engine oil. Normally, it is at the front of the engine and easy to spot. Essentially, the dipstick is there to help you when it comes to reading the amount of motor oil because it is a metal rod that goes down to the oil pan.
To ensure you get an accurate reading it helps to have a dry paper towel or an old rag handy. You then want to remove the dipstick and wipe away the oil from the entire rod, return it fully place, and then remove it again for examination. Note that there are markings on the dipstick to guide you on the amount of motor oil, usually, two notches or letters will be present on the lowest part of the dipstick. The middle space between the two markings is where you want your oil level to be.
If yours is below the first marking or not present at all you need to add oil or are simply due for an oil change all together. On the other hand, if yours is above the highest marking on your dipstick that indicates that you have too much oil in your engine and you will need to remove some.
Use a Funnel
It is tempting to get the bottle of motor oil and start to pour it straight into your vehicle. But, moving too fast is a sure-fire way to overfill it. You have to take your time and complete this process slowly. The best way to do this is to use a funnel. This is going to not only avoid a mess, but it will ensure that you are slowly refilling the engine oil allowing the oil to settle and distribute evenly throughout the engine.
Recheck the Oil
Some people fill up the motor oil by eye or just take add the first amount they see on the internet. My father always told me to “measure twice and cut once” as a child and I believe that lesson applies here as well. It’s not a bad choice to take what you read from in manual or internet as the right information but it’s always a good practice to double-check. Whether that is getting two separate sources of information or simply checking the dipstick after adding what you think is the right amount of oil. It never hurts to be sure in these situations. This way, you can enjoy peace of mind and know that you have not overfilled it.
How to Remove Excess Oil From Your Car
There are two simple ways to remove excess motor oil from your vehicle and they go as follows. The first is the easiest, and that is to take your vehicle to a mechanic that is close preferably. We do not want you to travel long distances with too much oil in your engine or it could lead to all the problems listed above. The second is to remove the excess motor oil yourself. This is done by crawling underneath your vehicle’s engine bay and locating the oil pan.
On the oil pan, you will notice a small single bolt that is usually between 15-18mm. With a wrench or a ratchet, loosen and remove the bolt above an oil pan or similar catch tray and slowly release the oil in small spurts. Between each amount released you want to return the bolt and then check the dipstick and repeat the process until your dipstick is showing the correct level of motor oil.
I will note that if you do not have the proper tools handy to perform the actions above I have found a nifty DIY video on YouTube which shows an interesting and effective way to remove excess motor oil from your engine.
Overfilling your motor oil can have a lot of bad consequences for your vehicle. Having too much motor oil is just as bad as not having enough in some cases so having the correct amount is paramount! This topic has to be one of the most avoidable and yet common circumstances I see far too often. In short, find the right information before attempting an oil change yourself. Whether that is contacting your manufacturer directly, finding credible resources online, or just take your vehicle to a certified mechanic. Read this article carefully and you will not make that mistake!
Thank you for reading and if you have any questions or comments on this topic please feel free to leave a comment below!
My name is Codi and I have been interested in automotive mechanics for as long as I can remember. Today I am a professional mechanic as well as a certified tire technician with over 10 years of combined professional experience.
I started this website because over the years I have noticed an increasing trend of false information among customers and automotive professionals alike. So I have gone to great lengths to provide the most factual information about tools, vehicles, companies, and other automotive products so that anyone can be provided with solid information on what they might be looking for.
I was born in South Florida and am currently located in Western Pennsylvania. I have seen how vehicles and tools respond to all types of weather conditions and scenarios over the years and I am happy to share every bit of automotive and mechanical knowledge I possess to help better inform the general public. Here at Mechanic Approved, our goal is to provide the best automotive mechanic information so that both customers and professionals can make better-informed purchases.