Most lubricants on the market today contain some sort of additive. But, what are these additives, and what do they do? In this guide, we’ll take a look at some of the more common additives found in lubricants, and explain their function. So whether you’re a business owner looking to optimize your equipment’s performance, or a technician looking to select the right lubricant for the job, this guide is for you!
The Difference Between Lubricants and Additives
Almost all lubricants on the market contain additives, which make up anywhere from 0.1% to 30% of their formula. Additives in lubricants serve many different purposes, but the main goal is always to improve the performance of a lubricant. Furthermore, these chemical compounds work with the base oils to improve consistency, increase durability, and provide essential support for your equipment.
What Are the Main Functions of Additives in Lubricants?
There are three fundamental roles that additives in lubricants serve:
- Boost the base oil’s good properties
- Curb the base oil’s less desirable properties
- Add properties that the base oil alone cannot provide
Some additives in lubricants, such as antioxidants, work within the body of the lubricant. Alternatively, other additives, such as antiwear and antirust, work on the surface of the metal of your equipment.
Common Additives in Lubricants
There is a long list of lubricant additives available today. Not only do they perform different functions, but they also have varied abilities to mix with the base lubricants and compatibility with other additives. Here is a quick list of the most common additives in lubricants and what they do.
- Anticorrosion – Decreases surface degradation of non-noble metals.
- Antifoaming Agents – Indirectly reduce oxidation by lowering air to oil contact.
- Antioxidant – Reduces oxidation of the lubricant, extending its life.
- Antirust – Lessens the corrosion of iron alloys.
- Antiwear – Creates a protective film to preserve loaded metal surfaces.
- Biocides – Helps manage bacteria growth in water-based lubricants.
- Color or Ultraviolet Dye – Provides a visual marker for inspection or testing for proper assembly.
- Conductive Agent – Produces electrical or thermal conductivity.
- Demulsifiers – Prevents water from mixing with lubricant allowing it to drain off more easily.
- Detergents – Aids in neutralizing acids and preventing deposits on metal components.
- Dispersants – Pairs with detergents to keep engines clean.
- Emulsifiers – Binds oil and water together, basically the opposite of a demulsifier.
- Extreme Pressure – Forms a protective layer to avoid seizure or damage of surfaces under pressure.
- Friction Modifier – Lowers the friction coefficient.
- High-Temperature Enhancer – Increases the high-temperature limit of your lubricant.
- Pour Point Depressants – Helps lubricants remain fluid at lower temperatures.
- Tackifier – Improves the lubricant’s ability to stick to moving parts.
- Viscosity Modifier – Changes lubricant viscosity.
We’ll dive deeper into some of these below.
Anticorrosion and Antirust
These additives in lubricants operate in two ways. First, they work to neutralize acids that develop over time in your lubricant. Second, they create a protective film on metal surfaces that repels moisture, further preventing rust or corrosion. It is important to note that certain anticorrosion and antirust additives work specifically for certain types of metal.
Oxidation is unavoidable, as it is a constant reaction present at all temperatures. However, oxidation increases at higher temperatures or due to water, wear debris, or other contaminants present in your lubricant. Antioxidant additives in lubricants slow the rate of oxidation by pairing with free radicals and peroxides, thereby breaking the cycle of oxidation and being consumed in the process. With these additives, lubricants can operate at higher temperatures and for longer periods of time.
Antiwear additives in lubricants adhere to metal surfaces when frictional metal-to-metal contact occurs. The heat created by the friction of contact activates these additives to form a protective film. If your equipment has relatively mild operating conditions, such as high speed and low load, then antiwear additives are a good fit. However, similar to antioxidant additives, antiwear agents are used up over time as they perform their function.
Extreme pressure additives in lubricants are like superpowered antiwear additives. They both function by forming a protective layer on surfaces and are used up in the process. But, as the name implies, extreme pressure additives are best for heavier loads, higher temperatures, and low speeds. As they are more aggressive, extreme pressure additives can actually cause corrosion of yellow metals. So, always check your equipment before using lubricant with extreme pressure additives.
Maintaining the right lubricant viscosity is critical to your lubrication management. So, viscosity modifier additives in lubricants are essential to prevent the loss of viscosity as the operating temperature increases. Also, they assist with lubricant flow at lower temperatures, which improves the lubrication at the start-up operation of equipment. The only issue with viscosity additives is that they are made up of large polymers that can get cut up by the shearing force of machine operation, lowering their functionality.
The Importance of Understanding Additives in Lubricants
Additives are an important part of lubricants, and they play a crucial role in keeping your equipment running smoothly. The science of additives in lubricants is a complex field, but it is vitally important in ensuring the proper function of machinery and your lubrication management. By understanding the chemistries and interactions of various additive types, you can choose blends that are best suited for your specific applications. This knowledge can help to improve machine performance and prolong component life. If you’re unsure of where to begin in choosing the right lubricant additives, there are many experts in the space that we would be happy to refer you to.