Oil Lubrication

oil lubrication
Tribology Wikipedia > Oil Lubrication

What is Lubrication?

Lubrication is the process of reducing wear and friction by applying a film that reduces friction between two surfaces in contact. The lubricant employed could be a solid, fluid, or plastic material. Oil is one of the widely used fluids in lubrication, thus the topic of this article is Oil Lubrication.

A variety of substances are utilized to lubricate surfaces. The two most common are grease and oil. Grease is made up of oil and a thickening agent that helps ensure its consistency, while the oil is used to lubricate as it is. Some additives may be added to the lubricating oil as per the application requirements. Oils may be mineral, synthetic, or vegetable-based, and a mix of the three.

The application decides which type of oil to be utilized. In the most extreme circumstances, synthetic oils may be helpful. In cases where the environment is concerned, vegetable oils or biodegradable oils also could be used.

The oil in the Lubricants contains additives that increase, improve or reduce the properties of their base oils. The number of additives used depends on the soil type and the purpose of the oil to be used.

The Function of the Lubricant

The most important purposes of lubricants are to:

  1. Reduce friction
  2. To prevent wear and tear
  3. Make sure the equipment is protected from corrosion
  4. Control the temperature (dissipate heat)
  5. The control of contamination (carries contaminants to a sump or filter)
  6. Transfer power (hydraulics)
  7. Provide a fluid seal

The reduction of friction is an essential goal of lubrication; however, this process has numerous other benefits. Lubricating films help prevent corrosion by shielding the surface from corrosive water and other substances. Additionally, they can play a significant role in preventing contamination in systems.

The lubricant functions as a conduit, through which it moves contaminants into filters to be eliminated. They also aid in temperature control by absorbing heat from surfaces and then transferring it to a lower temperature, where it will be absorbed and dissipated.

So, in this article, we will be talking more about oil lubrication and how lubrication with oil is a crucial and effective method in the tribology industry.

Lubricating oil

Lubricating oil, also known as lubricant or lube, is a group of oils used to decrease heat, friction, and wear of mechanical parts connected. Lubricating oil is utilized for motorized vehicles known for its role as motor oil and transmission fluid.

There are two main types of lubricating oils: synthetic and mineral. Mineral oils are the oil that lubricates, refined from naturally found crude oils. Synthetic oils are lubricating oils that are manufactured by the tribologists. Mineral oils that lubricate are currently the most widely used due to the lower cost of obtaining these oils from crude oil. In addition, the mineral oils can be produced to have different viscosities, making them suitable for many different applications.

Lubricating oils with different viscosities can be blended in this way, and it is the ability to mix the viscosities that make certain oils so beneficial.

Lubrication through oil

Lubrication with oil is typically used when extreme operating temperatures or speeds make it impossible to use grease. Also, the oil lubrication system is normally preferred if it is required to transfer the heat from the friction point, like gears.

During the operation, the oil is absorbed by rotating bearing elements, and after it circulates through the bearing, it is drained back into the oil bath. If your bearing remains stationary, the oil must be at a point that is about a quarter of the way from the level of the lowest rolling ball. When the speed is high, adequate oil must be able to reach the bearing to help eliminate the heat created through friction.

oil lubrication
Figure: Minimum oil level during bath oil lubrication method when bearing is in a stationary condition.

Additives for Lubricating Oil

Oils are consisting of base oil used for lubrication as well as additives.

Between 15 and 25% of additives present in the finished oils due to two reasons:

  1. To enhance specific characteristics of the base oil
  2. Or to add new properties to the base oil.

Anti-fatigue or Anti Wear (AW) Ingredients

These ingredients help to strengthen the ant fatigue properties of the oil. These additives are commonly employed to shield machine parts from damage and prevent metal loss due to friction in boundary lubrication. These are the POLAR additives and attach to frictional metal surfaces.

These additives react chemically with the metal surfaces when contact occurs under boundary and mixed lubrication conditions.

The molecules are activated through heat generated due to metal-to-metal contact and form a film that reduces wear. They also aid in protecting bases from the effects of oxidation and the metal from being damaged by acidic corrosive substances.

The antioxidant ingredients

The antioxidant ingredients can slow the process of oxidation that occurs in the lubricant. They also help prolong the intervals between oil changes by providing a stronger resistance to higher temperatures.

Detergent Additive

The detergency property of the additive helps to stop the development of deposits and neutralize acids that form in the oil. As a result, they increase the oil’s effectiveness and form the basis of the reserve alkalinity, especially in the engine oils, which prevents the combustion of char and oxidized compounds from forming gums or deposits on metal surfaces. The most recent additives are nitrogen compound polymers that don’t produce the ashes. However, these detergent additives should be utilized cautiously in fuel systems because their capacity to eliminate sediment deposits (calamine, for instance) can block the lubrication system.

Dispersant Additives

Dispersants dissolve solid impurities and help clean the burnt residues, gums, sludge and ashes, and deposits removed by detergents while the engine operates. In addition, they keep solid particles from aggregating and hinder sludge formation in the motor’s cold areas (carter). Dispersants are usually organic and completely ash-free. Therefore, they cannot be easily detected using traditional oil analyses.

These additives allow more acidic compounds to be neutralized and more contaminants to remain suspended. However, when these additives fulfill their roles of neutralizing acids and suspending contaminants, they’ll eventually outgrow their capacities and require the need for an oil change.

Anti-corrosion Additives

Anti-corrosion ingredients help shield ferrous metals from the combined attacks from oxygen, water, and some oxides created by the combustion process. The efficiency of a corrosion inhibitor will depend on the composition of the fluid, the amount of water used, and the flow pattern. It can be found in many over-the-counter products, often as sprays, which are paired with the addition of an oil lubricant. They can add to the water to prevent the leaching of copper and lead through pipelines.

A typical method to stop corrosion is to create an emulsion, usually a passivation layer that blocks access of the corrosive substance into the metallic.

Antifreeze Additives

Additives to antifreeze help the fluid stay liquid enough even at lower temperatures (from 15degC to -45degC). Common antifreeze can also raise the boiling temperature of liquids. However, most antifreeze additives also have lower heating capacities than water, limiting water’s capability to function as a coolant when added to it.

Water has excellent properties as antifreeze; water and antifreeze are utilized to cool internal combustion engines and other heat transfer applications, such as HVAC and solar heaters for water. The careful selection of the antifreeze will allow a broad temperature range where the mixture stays within the liquid state, which is essential for effective heat transfer and the correct functioning of heat exchangers.


Oil is one of the widely used lubricants, and it is used in a wide number of industrial applications like Compressors, Bearings, Engines, Gearboxes, Turbines, and many more. Lubricating oils in vehicles is also crucial to their functioning. If you have an adequately lubricated engine, it will require less effort into its moving pistons since the pistons move effortlessly. You will notice that your vehicle can run in the long term, using much less energy and operating at a lower temperature. In general, the correct use of lubricating oil inside the engine, car, or any other industrial application increases its effectiveness. It decreases the wear and tear of the internal components.


Nowadays, when we are moving ahead with energy efficiency projects and since lubricating oil is a valuable resource, many attempts have been made to recycle the old oils and use them as fresh oil. Recycled lubricating oils are used in “refineries,” which are where the water is extracted from the oil by the process known as dehydration. Impurities present in the oil – for instance, industrial fuels – are filtered out, and the oil is removed by vapor distillation. The extracted lubricating oils undergo a series of refinements to remove other impurities. After refinement, the oil is divided into different viscosities to allow for various applications.

The article is written by Riya Veluri, an editorial team member of Industrial Lubricants. After her graduation, Riya works as a website developer & SEO specialist in Lubrication & Tribology Industry & writes technical articles on Lubricants, Lubrication, Reliability & sustainability.