What Does Engine Oil Do?: The Power and Purpose Explained!

If you own a car, you probably know that you need to change the engine oil regularly.

But do you know why? What does engine oil actually do for your car, and why is it so important?

In this article, we will explain the role and benefits of motor oil, and how to choose the right one for your vehicle.

You will learn how oil lubricates, cools, cleans, and protects your engine.

Moreover, you’ll get to understand how it affects your car’s performance, fuel efficiency, and lifespan.

You will also discover the differences between conventional, synthetic, and blended oils, and how to find the best oil for your car’s make, model, and driving conditions.

By the end of this post, you will have a better understanding of what engine oil does, and why you should never neglect it.

So, let’s get started!

An image showing a technician pouring engine oil into a car engine. But what does engine oil do?
What Does Engine Oil Do?
Source: carparts

What Does Engine Oil Do?

Before you learn what oil does, you need to know the basics of how your engine works.

You don’t have to be an expert, but you should know that your engine has many parts that move and touch each other. This creates a lot of heat and friction.

Engine oil is the fluid that helps these parts move smoothly and stay cool.

Without engine oil, the heat and friction would make the engine melt and stop working.

This is called engine seizure or lock-up. When this happens, the only way to fix it is to get a new engine.

That’s why drivers make sure their car has enough motor oil to cover and protect the parts from wearing out too fast.

Besides the heat and friction from the moving parts, engines also use a process called internal combustion.

This process burns fuel and makes power, but it also makes water vapor, carbon, acids, and other things.

Long ago, engines did not have an oil pump to circulate the oil in the engine.

Instead, they used a simple system of scoops on the crankshaft that would throw oil up and coat the engine parts with oil.

However, this process was not very good, and often the engine would stop working after some time.

The method of oil distribution got better over time, but it took a long time for oil filters to become common in cars.

A filter helps get rid of unwanted bits in the oil, like carbon and metals.

Basically, Engine Oil plays a crucial role in this environment: not only does it lubricate the engine’s internal components to prevent overheating, but it also aids in maintaining cleanliness within the engine.

Importance of Oil Change

You need to change the engine oil regularly because it loses its effectiveness in performing.

Engine Oil Degradation

Initially, oil undergoes oxidation when exposed to air. This is a process accelerated by the significant heat within the engine.

Due to the intense heat, certain regions of the car experience faster breakdown of engine oil.

Consequently, this breakdown leads to the formation of sludge, which is essentially a carbon deposit that separates from the oil solution.

This sludge combines with the oil, causing it to become denser and compromising its lubricating properties.

Over time, the additives within the oil also degrade.

It’s important to highlight that excessively thin motor oil can adversely affect your engine’s performance.

Therefore, the oil should strike a balance, neither being too thick nor too thin.


As previously explained, oil plays a crucial role in engine cleanliness by absorbing carbon deposits, soot, or sludge.

However, there is a limit to how much of these byproducts it can absorb before reaching saturation.

Once saturated, the oil becomes unable to absorb any further material.

Consequently, soot begins to accumulate in the oil, which is why used motor oil appears black, and the oil progressively loses its efficacy.

An image illustrating Fresh Engine OIl vs Used engine oil

Dust and Dirt

It’s an undeniable reality that dust inevitably infiltrates various objects, a universal truth.

Anything in existence is destined to attract dust.

As debris builds up on the filter, which is intended to remove contaminants, it creates a barrier that hinders the oil’s flow through it.

Consequently, the oil absorbs more dust and its effectiveness diminishes.

This underscores the importance of changing the filter alongside the oil to maintain optimal performance.

Thankfully, most cars today have engine oil monitors that will alert you on your dashboard when your oil level is low or when you’re due for a change.

Many service centers will also stick a label on your window with the date of your next oil change.

What Is Synthetic Oil?

Synthetic engine oil is oil that undergoes a special chemical process.

Unlike regular oil, its molecules are more consistent in shape and have fewer impurities.

Typically, synthetic oil is better at resisting oxidation and performs well in extreme temperatures compared to conventional crude oil.

Fully formulated engine oil serves several purposes:

  • Lubricating and separating moving parts
  • Minimizing engine wear
  • Preventing deposits on engine components
  • Trapping dirt and contaminants in the oil until the next oil change
  • Cooling engine parts
  • Preserving fuel efficiency and performance
  • Offering protection in various temperatures
  • Acting as hydraulics in variable valve timing
  • Safeguarding the emissions system.

Can Switching Between Conventional and Synthetic Oils Lead to Engine Issues?

No, switching between conventional and synthetic oils does not cause problems for your engine.

As long as you use the right oil for your car and follow the manufacturer’s recommendations, you won’t experience engine issues.

However, synthetic oils usually offer better protection, performance, and longevity than conventional oils, so you may not want to switch back once you try them.

Additionally, synthetic oils are more resistant to oxidation, acidification, and sludge formation. This can damage your engine over time.

Therefore, switching to synthetic oil may be a good idea for your car’s health and efficiency.

Other Types of Engine/Motor Oil

Apart from synthetic motor oil, there are three other common types of motor oil:

  1. Synthetic Blend Motor Oil: This oil blends synthetic and conventional base oils, offering increased resistance to oxidation and better performance in colder temperatures.
  2. High-Mileage Motor Oil: Specifically formulated with additives to reduce oil burn-off and prevent leaks common in older engines, this oil is suitable for newer vehicles or those with over 75,000 miles.
  3. Conventional Motor Oil: Available in various viscosity grades and quality levels, conventional motor oil meets basic API specifications recommended by engine manufacturers but lacks the enhanced performance of synthetic motor oils.


Engine oil is the lifeblood of your car, and it performs several vital functions to keep your engine running smoothly and efficiently.

Besides lubrication, motor oil cools, cleans, and protects your engine from wear and tear, heat and friction, and harmful contaminants.

It also affects your car’s performance, fuel economy, and lifespan.

Therefore, you should always use the right type and amount of oil for your car.

Additionally, you need to change it regularly according to the manufacturer’s guidelines.

By doing so, you will not only save money on repairs and maintenance but also extend the life of your car.

Remember, engine oil is not just a fluid, it is a solution. So, don’t neglect it, and treat your car with the care it deserves.

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