What Are The Primary Functions Of Motor Oil?


The human nature of curiosity doesn’t let him live without questioning. Many questions come across in our minds when it comes to encounter automobiles and taking care of them. Like how to take care of my car? How to maintain the quality of the car’s engine? Which motor oil is good for my vehicle? What are the functions of motor oil? If you are searching for these questions – you’re at the right place.

Whether it is friction, degradation, or heating problems of the engine, there is a single solution to all of them – change your motor oil timely. No matter what engine oil does inside your automobile, there is one thing for sure that timely change of engine oil is as essential to your car as is a valentine gift to your love.

Before knowing about the functions of motor oil, it is essential to understand the composition of motor oil. Let take a quick look at it.

What are the ingredients of motor oil?

After extracting from the Earth, the crude oil is transported to the oil refinery, where its different components get separated. Here, a part is extracted during the process of refining crude oil called motor oil. The ingredients and composition of motor oil bring us to two things.

1. Base oil

The base oil, also called stock oil, is extracted from crude oil. The base oil is composed of thick and heavy petroleum hydrocarbons. If you were ever enrolled in high school chemistry, you might know that crude oil refinery for motor oil includes removing ingredients like wax, nitrogen, and sulfur.

The next process is the removal of unsaturated hydrocarbons. In the end, the base oil consist of hydrocarbon chains with 18-34 carbon atoms per molecule is ready to deliver to market.

An oil refinery plant extracting the crude oil under the water.

2. Additives

The base oil can be used directly in the original form as it comes from oil refineries. But in modern lubricants, almost all oil manufacturing brands insert oil additives in the base oil to enhance its qualities.

Motor oil additives are the chemical compounds added to a base oil to improve motor oil functions. These improvements play a significant role in a better way to fulfill user requirements. The only reason for using additives is to meet up with user needs precisely.

Additives include various combinations like anti-oxidants, viscosity index improvers, extreme pressure additives, rust and corrosion inhibitors, anti-wear agents, anti-foaming agents, and dispersants and detergents.

Different engine oil additives are displaying on a shelf.

How is synthetic motor oil made?

Synthetic motor oil is made from chemically modified petroleum under controlled lab conditions. Besides, some other compounds such as Polyalphaolefins are also added to it to improve its efficiency.

Manufacturers packed the synthetic motor oil alone or in combination with conventional motor oil. However, every manufacturer keeps its synthetic oil composition and ratio of additive substances secret and never discloses its specific formula.

Functions of motor oil

Today engines are becoming more sophisticated, compact, efficient, and economical. To meet up with all of these advanced engines’ features, engineers also adopt many advancements in the manufacturing of motor oil. The purpose of these advancements is totally to maximize engine efficiency and hence give us economic relief.

Functions of motor oil include lubrication, enhanced cleaning power, cooling capability, friction reduction, corrosion reduction, energy transmission, shock dampening, air tightening capability, controlling the emission of harmful gases, etc. 

1. Lubrication

The primary function of motor oil is to lubricate the engine components. The motor oil lubrication property prevents the metal-to-metal contact within the engine, thus lowering the wearing and friction process and ultimately reducing its heat.

If the motor oil’s lubricating ability decreases over time or there is no lubrication within the metal parts, then the engine’s seizing or scuffing can occur due to the metal transfer. So it’s always better to change your engine oil on time.

2. Cleaning power of motor oil

Good motor oil always removes impurities (such as sludge, dust, and rust, etc.) from the engine components.

Sometimes the engine needs repairs. After repairs, it may get contaminated with small metallic particles with other impure substances such as dust and sand. Motor oil removes all of these contaminants and impurities from the engine, including other metal particles getting from wear and tear.

Furthermore, engine oil tries to avoid these contaminants from contacting the engine’s components while running. Impurities suspended in motor oil are filtered out during the oil filtration system or through oil changes.

Cleaning an engine with motor oil also involves solvency (ability to dissolve liquid, solid, or gas) of motor oil. Good solvency helps in dissolving and suspending all impurities in the oil.

Good motor oil itself has excellent cleaning capability. But we can further enhance it by adding dispersant and detergent.

The dispersant is a solvent that dissolve contaminants and avoid sludge formation hence maintained the cleanliness of oil.

Detergents prevent contaminants from adhering it to a piston, piston ring, or overall assembly.

Both of these additives, in return, increase the solvency and overall cleaning power of motor oil.

3. Cooling capability of motor oil

Whenever running parts of any machinery, including engine, are considered – there arises an issue of getting hot. A vehicles’ engine is the place where the most severe, intense, fast, and sudden movements occur, due to which it gets hot.

Thus, motor oil plays an essential role, i.e., it provides the constant cooling capability to all those running parts such as pistons, cranks, shafts, rings, etc. Motor oil also maintains the temperature of all those parts of the engine and avoids sparks or fire.

4. Frictional reduction

Running parts of an engine not only produce heat but also generate friction. Friction can cause breakages as well as wear and tear damages. Motor oil smoothens all the movements by lubricating surfaces.

The engine parts which are in contact under movements are also lubricated. Good motor oil establishes a thin layer among these surfaces under movement and reduces friction between the components.

This sticky nature of motor oil enables it to reduce the friction between the engine components significantly.

The anti-wear additive agents present in the engine oil also helps it to reduce friction. It also enhances the performance of engine oil during cold-starts.

5. Corrosion (rusting) reduction

Whenever it comes to metals, there arises a significant issue of corrosion. Most of the engine components are made of metals like cast iron, structural steel, alloys, and aluminum. So they are more likely to get eroded.

Corrosion can be prevented by forming a barrier between potentially corrosive metal and the catalyst accelerating corrosion. A second way to prevent corrosion is by neutralizing corrosive elements chemically, especially oxygen.

Good motor oil has the capability of avoiding all such internal component’s corrosion. A thin film formed by motor oil establishes a barrier among metal and catalyst elements like oxygen. Here anti-oxidants and corrosion inhibitors found in the form of additives in base oil also play a significant role in reducing corrosion (rusting).

6. Efficient energy transmission

The incompressible nature of motor oil enables it to transmit energy without absorbing it. When pistons move, they exert very high pressure on the motor oil flowing in them. The incompressible nature of motor oil plays a significant role in encountering such high pressure without absorbing pistons’ energy. Thus, motor oil acts as an energy transmission agent and reduces the engine’s heat.

Sports geeks use extreme pressure additives along with base oil to achieve even better results.

7. Shock dampening

Repetitive motions inside the engine result in the production of mechanical shocks. Without effective damping, they can continuously increase to dangerous levels by superposition of each movement.

Good motor oil eliminates those mechanical shocks by damping in return, saving the engine to disassemble. Motor oil also increasing the overall life of the engine by damping such motions.

8. Air tightening capability

Using rubbers and rings can minimize the narrow slots exposing the engine’s interior to the diffusion of environmental gases. As long as external gases can move into the chamber, the engine is in constant danger of damage.

Another function of motor oil is closing such microscopic openings, thus minimizing this continuous danger to the engine. Ultimately, the motor oil saves the main body of the engine internally from exposure to environmental gases.

Motor oil also creates hydrodynamic seals that help to keep the combustion chamber isolated from the combustion gases. In return, it maximizes engine performance and efficiency.

9. Controlling the emission of harmful gases

Today’s technology is getting very advance. Engines are no more like those dark smoke-producing types of machinery due to the thankful advancement in motor oil.

When engines produce harmful gases like carbon dioxide, motor oil controlled their emission. The amount of emission of toxic gases and unburnt fuel depends upon engine oil. According to a study, timely change, properly leveled, and low viscosity motor oil has proved to produce less harmful gases.

The friction between the moving metal parts increases if there is a low level of motor oil. This excessive friction consumes engine energy internally before its transmission to the wheels. Thus it decreases the engine efficiency with excessive production of unfriendly gases (higher gas emission).

The same rule could be applicable in the case of higher viscosity of motor oil. So it is advised that always use low viscosity motor oil. But keep in mind that always consult your owners’ manual to check the recommended engine oil regarding its type and viscosity.

To reduce the emission of gases, i.e., to lessen your engine smoke, you can use additives like viscosity inhibitors or buy less viscous base oil.

Different types of engine oil displaying at an oil store.

Exclusive functions of motor oil

Motor oil saves the vehicle owner from costly repairs because without using it, the engine can get severe damages in seconds. Good quality motor oil offers the following exclusive benefits too.

1. Protect the engine

Corrosion inhibitors protect the engine from rusting and sludge as oil begins to oxidize. Thus improve engine efficiency and protect it from severe damage.

2. Improve fuel efficiency

The thin oil film made by motor oil reduces the friction between the moving metal parts. This reduction in friction also improves fuel efficiency.

3. Longer engine lifespan

Due to its cleansing characteristics and friction reduction properties, good motor oil ensures a longer engine lifespan. Motor oil avoids clogging and hence prevents damages. Motor oil prevents the engine parts from rusting, in return, enhanced the engine performance and ultimately prolong its lifespan.

4. Smooth engine running

A lubricated engine runs better and smoother. Motor oil prevents the engine from severe damages mechanically. Using good motor oil maintains the cost of repairs and gives extraordinary results in efficiency and performance.

5. Stabilized temperature

As the motor oil reduces the friction between the moving metal parts, heating is also suppressed down within the engine. Hence another function of motor oil is to cool down the engine temperature and keep it stabilized.

Always change your engine oil on time.

Motor oil gives better lifespan, efficiency, and performance to the engine. It affects many engine properties positively, like corrosion, cleansing, cooling, and emission. It also has a beneficial role in energy transmission and smooth running due to its friction reduction and air tightening capabilities.

Like anything in this world, motor oil also has a lifespan, and it is essential to timely change it as it saves the engine itself from self-contamination.

Timely checking the motor oil quality and its level is a good practice, though. You can visit our other articles to learn better techniques to keep a check on motor oil.

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