Engine Oil: An Overview

Engine Oil Additives: What Are They & How Do They Work?

Additives are chemical compounds blended into base oils to provide them with beneficial properties and enhance their performance.

Some additives introduce unique properties to the oil while others are designed to address specific issues. Some types of additives are specially formulated to slow down unfavorable changes that can occur in the oil over time.

The usage of additives has been a revolutionary practice; these multifunctional compounds have enhanced the efficiency of motor oils and solved a range of engine problems.

Almost all commercially manufactured motor oils contain some amount of additives. The exact volume varies according to the application and needs of the engine being lubricated. Typically, additives can make up 0.1% to 30% of the final lubricant’s composition.

So, how do additives really work? The following section will delve into the key characteristics of additives and explore the different types of agents that can be found in different additives.

Polar Additives

The term ‘additive polarity’ refers to the innate tendency of additive molecules to be attracted to other polar substances that may come in contact with oil.

This means that once additives have completed their task of mitigating the effects of contaminants, they cannot be regenerated and need to be replenished in order to maintain the performance of the lubricant.

Therefore, it is crucial to consider the amount of pollutants present in the environment where the additives are used. When exposed, the additives will adhere to different contaminants like silica, dirt, or water, and eventually be filtered out.

Polar Mechanisms

Particle enveloping, also known as particle encapsulation, is an important mechanism in which the additive clings to the surface particles of a fluid and envelopes them.

These particles often include dirt, soot, or other debris present in the lubricant. By enveloping these particles, the additives can prevent them from agglomerating, settling, or depositing within the lubricant.

Metal wetting is another mechanism that is utilized by certain additives to improve lubrication and reduce wear and tear.

These additives are designed to improve the ability of a fluid to spread evenly across a metal surface. Many lubricants and fluids including engine oils, gear oils, and hydraulic fluids contain metal-wetting additives.

Types Of Engine Oil Additives

Here are some of the most common additives used in conventional motor oil:

Anti-oxidants. The oxidation process is catalyzed at high temperatures with the presence of metal and water. These additives prevent the motor oil from degrading after exposure to oxygen, thereby increasing its longevity.

Rust & Corrosion Inhibitors. Changing temperatures in the engine can lead to the buildup of moisture. As a result, corrosion and rust can form, leading to impaired engine performance. These additives form a protective coating on metal surfaces to reduce or eliminate the formation of rust and corrosion.

Viscosity Index Improvers. Made from large polymers, viscosity improvers prevent oil from thinning out at high temperatures. As they heat up, these polymers expand and thicken the oil to maintain its original viscosity. Similarly, as temperatures decrease, the polymers contract to ensure consistent viscosity across a range of temperatures.

Anti-wear Agents. This is an important class of additives that reduces friction and wear between metal surfaces. These agents work by attaching to metal surfaces and forming a protective layer on them.

When the metals come in contact with each other, heat is generated. This activates the anti-wear agents to carry out their intended function. Once completed, the additive will get depleted which may lead to a rise in wear damage.

Extreme Pressure Additives. These additives function similarly to anti-wear agents as they also create a film on metal surfaces to prevent adhesive wear. However, they are chemically more aggressive and are designed to be activated under higher loads and temperatures.

Extreme pressure additives often contain compounds of sulfur and phosphorus which give the oil a distinct, strong smell.

Detergents. These additives play an important role in preventing sludge buildup over time. Detergents have an alkaline or basic nature which allows them to neutralize acids that can form in the oil. The detergents dislodge and remove sludge and other impurities which helps the engine operate at optimal levels.

Anti-foaming Agents. These agents prevent the undesirable effect of foaming in lubricants which can lead to enhanced oxidation and reduced lubrication levels. Anti-foaming additives contain chemicals possessing low interfacial tension which weakens the bubbles and makes it easier for them to burst.

Friction Modifiers. The main purpose of friction modifiers is to alter the level of friction between the engine and transmission components. These are similar to anti-wear additives, however, they are meant for lower loads and are not activated by high temperatures.

Pour Depressants. The pour point of oil refers to the minimum temperature at which it can retain a fluid-like consistency. Wax crystals present in oils tend to crystallize at lower temperatures. If they get too thick, it can affect the oil’s viscosity and functionality.

Pour depressants are additives that interact with the wax crystals and modify them to maintain low-temperature fluidity and performance.

Emulsifiers. These additives help to stabilize and bond metal working fluids into a suspension called an emulsion. Emulsifiers reduce the surface tension between these fluids and bind them together so they do not separate.

The Verdict

There is a vast variety of additives and conditioners with the potential to enhance lubricants and make them last longer. Many after-market oil additives make claims of increased horsepower, reduced engine wear, better fuel economy, and other additional benefits.

When selecting and using these additives by yourself, it is very important to exercise caution. In fact, it is better to leave chemical manipulations up to the professionals rather than trying to mix them on your own.

Oil manufacturers and those with expertise in the field possess the technical know-how to add the same compounds in precise quantities, at controlled temperatures, and under specific conditions to give the lubricant the desired properties.

Benefits of Engine Oil Additives

As noted above, additives play a crucial role in improving base oil performance. Without these additives, your car engine’s oil would likely face a host of issues such as contamination, leaks, and reduced ability to protect critical engine components.

It is worth mentioning that engine oil additives are especially beneficial for vehicles that are older or not in optimal condition.

To sum it up, engine oil additives have three main benefits:

  • Protecting metal surfaces from excessive friction, wear, corrosion, and rust.
  • Expanding the lubricant’s application range and keeping it stable under demanding operating conditions like high loads and extreme temperatures.
  • Extending the lifespan of the lubricant.
Common rules of additive usage

At times, the use of after-market additives can result in the nullification of oil and equipment warranties. The reason is, the final composition of the lubricant is not tested or approved and may potentially have unforeseen effects.

Here are some crucial precautions to take if you use after-market additives.

    1. Do not attempt to convert an inferior lubricant into a premium product with the use of additives. You cannot overcome an oil's subpar lubricating qualities by simply incorporating an additive. A more viable solution would be to purchase a high-quality engine lubricant in the first place.
    2. Base oils have a finite capacity to carry and dissolve additives. If an oil is already saturated with additives or has a low level of solubility, the additive will settle at the bottom or may not dissolve completely. This can lead to the additive being ineffective and in some cases, negatively impacting the performance of your oil.
    3. Find out if there is a specific lubrication problem and what may be causing it. If it can be solved or improved with the help of an additive, then look for one that directly addresses the issue.
    4. Pick the right additive or oil conditioner. Take some time to research the brand, composition, and compatibility of the product with your vehicle’s engine.
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