Lubricants Additives Comprehensive Guide

The Importance of Additives in Lubricants: A Comprehensive Guide

Lubricants are essential for the smooth functioning of engines in vehicles, machinery, and equipment. However, not all lubricants are created equal. While basic lubricants offer protection, lubricant additives can significantly improve engine performance and longevity.

So, what are additives in lubricants? Let’s jump right in.

Additives are chemical compounds added to small quantities of lubricants to enhance their performance. These compounds are specifically designed to address various issues that can affect the performance of engines.

Lubricants are essential for reducing friction and wear between moving parts in machines and engines. They also protect against corrosion, oxidation, contamination, and high temperatures. However, lubricants alone cannot meet all the demands of modern applications. That’s why additives are added to lubricants to enhance their performance and extend their service life.

Additives are organic or inorganic compounds that are dissolved or suspended as solids in oil. Depending on the machine, they typically range between 0.1 to 30 percent of the oil volume. Additives have three basic roles:

  • Enhance base oil properties with antioxidants, corrosion inhibitors, anti-foam, and emulsifying agents.
  • Suppress undesirable base oil properties with pour-point depressants and viscosity index (VI) improvers.
  • Impart new properties to base oils with extreme pressure (EP) additives, detergents, metal deactivators, and tackiness agents.


Antioxidants are additives that prevent or slow down the oxidation of base oils by reacting with oxygen or radicals. Oxidation is a chemical process that causes oil degradation, sludge formation, viscosity increase, acidity increase, and corrosion. High temperatures, metal catalysts, water, and contaminants can accelerate oxidation.

Antioxidants can be classified into two categories:

  • Primary antioxidants: Primary antioxidants scavenge free radicals that initiate oxidation reactions. Some examples of primary antioxidants are phenols (such as butylated hydroxytoluene), amines (diphenylamine), and hindered phenols (tert-butylhydroquinone).
  • Secondary antioxidants: Secondary antioxidants decompose hydroperoxides formed during oxidation into stable products. Some examples of secondary antioxidants are zinc dialkyl dithiophosphate (ZDDP), sulfurized olefins, and phosphites.

Corrosion Inhibitors

Corrosion inhibitors are additives that protect metal surfaces from chemical attack by water, acids, or other corrosive agents. Corrosion can cause pitting, rusting, scaling, and metal parts wear. Corrosion can also contaminate the oil with metal particles.

Corrosion inhibitors can be classified into two categories:

  • Anodic inhibitors: Anodic inhibitors form a protective film on the anode (the metal surface that loses electrons) to reduce its dissolution rate. Some examples of anodic inhibitors are carboxylic acids (such as stearic acid), phosphates (such as trisodium phosphate), and chromates (such as sodium chromate).
  • Cathodic inhibitors: Cathodic inhibitors reduce the rate of reduction reactions at the cathode (the metal surface that gains electrons) by scavenging oxygen or forming insoluble compounds. Some examples of cathodic inhibitors are nitrites (sodium nitrite), borates (sodium borate), and molybdates (sodium molybdate).

Oil-Based Anti-Foam Agents

Oil-based anti-foam agents have an insoluble oil carrier in the foaming medium. Oil-based anti-foam agents work by forming a thin film on the surface of the bubbles and weakening their stability. The film also reduces the surface tension of the liquid and increases its drainage rate. Oil-based anti-foam agents are effective against macroscopic foam (visible foam at the surface) and microscopic foam (entrained air bubbles in the bulk liquid).

However, they can cause drawbacks, such as increased viscosity, reduced filterability, seals and gasket contamination, additives interference, and reduced biodegradability.

You’re In A Never-Ending Battle For Benefits

One of the primary benefits of additives in lubricants is that they can help reduce engine wear and tear. The additives create a protective barrier between the engine parts, reducing the friction and heat generated during operation. This, in turn, can help prolong the engine’s life and reduce maintenance costs.

Well Performance Under Varying Temperature Conditions

In addition, additives can help improve the lubricant’s viscosity and stability, ensuring that it performs well under a wide range of temperatures and operating conditions. They can also help to prevent the buildup of deposits, such as sludge and varnish, which can clog oil passages and cause engine damage.

Reducing The Friction And Improved Fuel Efficiency

Oil additives can improve engine performance in several ways. For example, some additives can improve fuel efficiency by reducing the friction between the engine parts. This can lead to better mileage and lower emissions, which is great news for the environment and your wallet.

No Engine Noice

Another benefit of oil additives is that they can help to reduce engine noise and vibration. This can lead to a smoother, quieter ride, which is especially important for drivers who spend much time on the road.
Oil additives can also help to progress the performance of older engines that may be experiencing issues such as leaks or reduced power output. Adding the right combination of additives can help restore your engine to its former glory and extend its useful life.

What’s the bottom line? Lubricant additives are essential for proper functioning and maintaining engines. They can help reduce wear and tear, improve fuel efficiency, reduce engine noise and vibration, and extend the engine’s life. So, if you want to keep your engine running smoothly for years to come, choose lubricants that contain high-quality additives.