What Happens if You Put Too Much Oil in Your Car?

Engine oil is unquestionably the lifeblood of every vehicle. It is the one substance that keeps moving parts in an engine functioning properly. It reduces friction and slows down component wear and tear. As if that were not enough, engine oil also improves your vehicle’s gas mileage and overall performance. But what if you put too much oil in your car?

If your engine has too much oil, you will likely hear clattering or metal-on-metal noises from the engine bay, observe odd vehicle performance behaviors, or experience engine overheating. Some indicators of these consequences include recurring oil leaks and smoke from the engine block or exhaust.

This article will not only discuss the aftereffects of overfilling but also ways to resolve engine oil overfilling, factors that affect oil consumption, and oil capacities per vehicle.

So if you want to further understand the processes inside your car, then sit back and let this guide educate you on how important it is to keep your engine oil levels in check.

What Happens if You Put Too Much Oil in Your Car?

1. Clattering and Other Engine Noises

One of the more apparent causes of too much engine oil is engine noise. By no means is it exclusive to the problem. But it is a guaranteed outcome of engine oil issues.

A noisy power mill usually results from foamy engine oil running through the lubrication lines and failing to coat engine components the way it should. Engine noises do not necessarily indicate a grave problem right away, but they can be pretty annoying (especially if they repeatedly occur while driving).

2. Increased Oil Temperature

The foremost outcome of having too much oil in your car is increased oil temperature. The issue starts when excessive engine oil causes the crankshaft to dip into the oil sump, goes on to being recognized by your car systems as inadequate lubrication, and eventually translates into increased flexing work and splashing inside the engine.

Rising oil temperature is ultimately the result, which also gives birth to other complications.

3. Severe Friction on Engine Components

While sufficient lubrication protects various engine parts from premature wear and tear, too much of it can result in component damage due to increased friction and resistance experienced by the crane and crankshaft.

Different engine components have varying friction and resistance thresholds based on several factors. It would be too technical to explain these thresholds in this guide (it is better for mechanical engineers to take over).

But what is noteworthy is that excessive engine oil quantities are guaranteed to disrupt the balance among these facets.

4. Added Pressure on Crankshaft Couplers

The head and tail couplers on crankshafts are engine components that prevent (if not halt) oil leakage, provided the amount of oil is within spec.

But when engine oil becomes excessive, these couplers fail to do their job. Things get worse when the leakage occurs on the flywheel end of the shaft, as contaminated oil can damage the clutch if left unaddressed.

5. Engine Wear

Incorrect engine oil quantities create a domino effect, leading to incorrect oil pressure and further translating into increased (or hastened) engine wear.

Engine wear is one of the earlier indications that a car’s oil reservoir has been overfilled with motor oil (and left that way) for far too long. But it may not be too late for the engine if the issue is addressed at this stage.

6. Engine Damage

This will be the likely outcome if you fail to check your oil levels at the first signs of engine wear. It may seem far-fetched, but engine damage can happen sooner than you think. Too much oil in a car leads to reduced lubrication. When oil levels reach the crankshaft, the latter ends up aerating the oil and turning it into foam.

Apart from reduced lubrication, this frothy engine oil can wreak havoc on components like the crankshaft exhaust pipe (view on Amazon), suction hose, combustion chamber, valve pipes, and engine rods. The last two, in particular, become bent or collapse due to destabilized oil pressure (due to excessive oil) or incompatible engine oil entering the cylinder resulting in a hydrolock.

7. Overheating

Frothy engine oil caused by excessive quantities results in premature engine wear and damage and engine overheating. The latter is a later-stage aftermath of having too much oil in the engine. It is typically characterized by engine seizing or failure of the affected vehicle to run at all.

Sadly, this problem often emanates from something as simple as neglecting to utilize the oil dipstick when periodically checking engine oil levels.

8. Acceleration Peculiarities

One of two things can happen to vehicles with overfilled engines, and the probable outcome largely depends on whether the car is gasoline-fed or diesel-fed. Petrol-fueled engines end up working harder to overcome added resistance from parts scraping.

Diesel-powered mills develop an auxiliary fuel supply due to oil overfilling – causing the engine to accelerate abnormally to the point of mechanical failure. The second scenario is rather troublesome, as there is no way to halt this acceleration other than blocking the vehicle’s air intake.

9. Failing Seals and Gaskets

Another concern about frothy engine oil resulting from excessive amounts is its adverse effect on seals and gaskets.

Functionally, these parts should be able to keep a certain level of oil pressure away from particular areas inside your vehicle’s engine. But if seals and gaskets get overpressurized, they can give way to these restricted areas, translating into oil leaks, gases escaping from the combustion chamber, or, worse, blown head gaskets.

10. Clogged Catalytic Converter

When excessive engine oil finds its way into the combustion chamber or your car’s exhaust system, it will eventually reach your catalytic converter (view on Amazon). And since catalytic converters are very hot, oil burning in the cat occurs.

This event hinders the catalytic converter’s design, which is to reduce the toxicity of exhaust gases. Either that or your catalytic converter becomes plugged. Neither situation is the lesser evil, as both would warrant a costly catalytic converter replacement.

11. Spark Plug Fouling

Excessive motor oil in your vehicle’s engine system will inevitably result in leaks making their way into other car systems, like your electricals. Once this happens, you may notice fouled spark plugs the next time you inspect them or service an electrical component.

Fouled spark plugs are one of the things you would least want to have as they compromise spark ignition and cause misfires, rough idling, and starting issues. There is no way to clean or repair fouled plugs. So automatically, they will have to be replaced.

Given these consequences, it is best to strictly adhere to OEM recommendations on engine oil quantities. After all, these companies designed your vehicle and, therefore, know all about its intricacies and limitations.

Following what is in the owner’s manual will not only save you from needless headaches and guarantee your safety on-road but also prevent the occurrence of the abovementioned problems.

Engine Oil Capacities per Vehicle Type

As with other fluids, the amount of engine oil required for your vehicle is specific to its make, model, and engine type. It is rare for its capacities to be similar to another unless the car in question has the same OEM and is equipped with same-spec power mills.

The figures below are based on top brands for 2022 and do not constitute an exhaustive range of engine oil requirements per vehicle. They also depend on engine type, with lower-limit values being true for 4-cylinder engines and upper-limit ones for 6-cylinder power mills.

Your service manual is still the best resource for knowing how much oil your car needs. Nonetheless, these details would be handy if you need a quick reference to keeping your engine oil levels in check.

How Much Engine Oil Do I Need?

Vehicle Type/s	Volume (US Quarts)	Volume (Liters)
Green/Eco Car, Electric Vehicle (EV)	N/A	N/A
City Car, Family Car, Sedan	5.0 – 8.0 US qts	4.7 – 7.6 L
Convertible, Roadster	3.4 – 7.9 US qts	3.2 – 7.5 L
Coupe, Muscle Car	4.2 – 11.6 US qts	4.0 – 11.0 L
Estate Car, Station Wagon, Touring	4.1 – 8.0 US qts	3.9 – 7.6 L
Hatchback, Liftback	3.2 – 10.0 US qts	3.0 – 9.5 L
Limousine	4.8 – 30.6 US qts	4.5 – 29.0 L
Microcar	3.3 – 5.9 US qts	3.1 – 5.6 L
Minivan, Crossover Utility Vehicle (CUV)	3.7 – 7.2 US qts	3.5 – 6.8 L
Pickup, Commercial Vehicle	3.2 – 8.5 US qts	3.0 – 7.6 L
Sports Utility Vehicle (SUV), Subcompact Car	3.7 – 8.0 US qts	3.5 – 7.6 L
Supercar, Exotic/Sports/Race Car, Grand Tourer (GT)	4.5 – 11.6 US qts	4.2 – 11.0 L

When Is the Engine Too Full of Oil?

Going over the recommended quantities specific to your vehicle is equivalent to overfilling. Additives and cleaners in your engine oil (or going ham with sea foam) can cause your car to give off “too much oil” symptoms or render your oil levels to show above the full mark on the dipstick.

But there are other ways you can tell if your engine contains excessive amounts of oil, as follows:

Too Much Oil in Car – Symptoms 

• Oil leaks
• Smoke from the engine or exhaust (either white, blue, or black)
• Burning oil smell
• Activated “High Oil Pressure” light
• Misfires, rough running, and stalling
• No-start or starting issues
• Erratic or “confused” oil gauge behaviors

Indicators aside, the most accurate way of determining whether your engine is too full of oil or not is with the use of an oil dipstick. If your oil levels exceed 1/8th of an inch above the high/full mark, it is time to drain the excess oil.

While at it, inspect the quality of the drained oil and see if your engine requires a seal/oil filter replacement or flush. Otherwise, do the following steps to bring your engine oil level down to spec:

How Do You Fix Overfilling?

If you are driving, park in a safe spot and switch off the engine. Remove the excess oil from the engine via a suction pump or by loosening the drain plug or oil filter.

If draining via a drain plug, refer to the steps below:

1. Jack up your car.
2. Locate your vehicle’s drain plug.
3. Place an oil container or drain pan underneath it.
4. Partially open the drain plug and let the oil out for a few seconds.
5. Recheck the oil level if it has gone down to normal.
6. Do steps #4 and #5 repeatedly until the engine oil level is up to spec.
7. Securely close the drain plug.
8. Measure the oil quantity after two minutes, just to be sure.
9. Repeat steps #3 and #4 if your car is still overfilled.
10. Replace the drain plug (use a wrench if necessary).

If draining using a suction or extractor pump, refer to the steps below:

1. Increase engine oil temperature by leaving your car on for a few minutes.
2. Insert the pump tube into your vehicle’s dipstick hole.
3. Spread a cloth or rag around the hole to avoid making a mess.
4. Start the suction/extractor pump, and take out the needed quantity of engine oil.
5. Remove the pump tube from the dipstick hole once done.

If you have over-drained, refill your oil reservoir below the maximum level. But do so incrementally to avoid overfilling your engine again.

A slight overfill (for instance, two millimeters above the full mark) would probably not cause any issues, as the excess oil can be easily burned off after driving for a few hundred miles. But to side with caution, it is ideal to keep your oil levels between the low and full markers on your dipstick.

Factors Affecting Engine Oil Consumption

Owners sometimes resort to overfilling to offset drastic engine oil consumption behaviors in their vehicles. While the thought process behind this is understandable, it will never effectively remedy such a scenario.

If you ever observe your car consuming engine oil faster than normal, it would make more sense to check the integrity of your lube lines or the condition of the actual engine. Otherwise, take the factors below into account when choosing a variant and only fill your vehicle adequately:

Oil Quality

The engine oil quality in your vehicle matters, as poor-quality variants can lead to high oil wastage and premature wear of your power mill’s friction parts.

Some engines may do okay with off-brand, conventional motor oils. But if your car is used as a daily driver, as an off-roading buddy, or for commercial applications, then stick to API-certified name brands that meet manufacturer-provided criteria.

Viscosity

The thickening and thinning rate of engine oil is another facet that determines just how much your vehicle needs. If your engine is intrinsically a cold starter, winter-grade oils are the most suitable for use (and will probably be your OEM’s recommendation).

Conversely, incompatible multigrade oils only lead to thermal breakdown and deposit formation, unnecessarily increasing your car’s engine oil consumption.

Engine Complexity

This, right here, explains why 4-cylinder and 6-cylinder power mills differ in their engine oil requirements. Engine systems with more complex valvetrain and cylinder arrangements naturally require higher oil quantities to run smoothly and scathe-free.

In like manner, there would be noticeable disparities in oil requirements between gasoline-fed and diesel-fed engines.

Volatility

Evaporation loss in lubricants is inevitable since it is eventually burned off by your car. However, certain engine oils are less volatile than others, so you should go with these variants (especially if you live somewhere with higher outside temperatures).

These factors, alongside other oil properties, are taken into account by your car manufacturer when providing engine oil recommendations. That said, there shouldn’t be a reason for you to go over suggested oil levels when topping off your four-wheeler.

Couple adequate oil levels with periodic oil changes, and your vehicle’s strange engine oil consumption should resolve quickly.

Conclusion – What Happens if You Put Too Much Oil in Your Car?

In truth, engine oil overfilling can be easily averted – if only car owners religiously stuck to their oil change schedules and used their oil dipsticks properly. But it is not always the vehicle owner to blame.

Sometimes, overfilling results from negligence by a professional mechanic. Other times, components of our engine system simply deteriorate with age.

For any of these situations, regular vehicle inspection plays a big part. Even if troublesome symptoms do not appear, it is wise to examine car components more abused than others to pre-empt overfilling and its aftereffects.

Not skimping on the quality of engine oil used makes a huge difference, too, as high-quality oil tends to leave less soot along the lube lines and cylinders. Most importantly, promptly resolving engine overfilling can help save you from suffering costly repairs and a slew of engine problems.