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Base Oils

Base oils can be manmade, synthetic, or derived from crude oil, non-synthetic. The top five importers of crude oil to the US are: Canada ($7.05B), Mexico ($1.71B), Saudi Arabia ($946M), Nigeria ($466M), and Ecuador ($458M). Base oils are then refined to remove any unwanted components or impurities in order to create a pure and stable base oil. Base oils are the primary component of lubricants and, once mixed with specific performance additives, create lubricants for a wide range of applications.

Common types of base oils include:

Polyalphaolefins (PAOs)

  • PAOs are synthesized by polymerizing alpha-olefin monomers. Characterized by excellent high-temperature stability, low volatility, and good lubricity. PAOs, which are Group IV, are widely used in automotive and industrial lubricants.


Polyalkylene Glycols (PAGs)

  • PAGs are produced by the reaction of ethylene oxide or propylene oxide with glycols. They exhibit excellent lubricity, high viscosity index and good thermal stability. PAGs are commonly used in compressor oils and automotive gear lubricants



  • Esters are derived from the reaction of organic acids with alcohols. They offer excellent lubricity, high viscosity index, and good thermal stability. Esters find applications in aviation lubricants, refrigeration oils and high-performance automotive lubricants.



  • Diesters are used for low-carbon formation at high temperatures and improved additive solubility.



Additives are compounds that are formulated to customize the performance and properties of lubricants for specific applications. Additives generally make up between 0-65% of a lubricant, depending on its application. Additives can be broken down into 3 basic categories: additives that protect against oxidation, additives that add to or improve the properties of the base oil or additives that protect metal surfaces.


    These additives form a protective film on metal surfaces, reducing friction and preventing wear and damage to the equipment. They are used in engine oils, compressor oils, hydraulic oils, greases, transmission fluids and many industrial lubricants.


    Antioxidants prevent the lubricant from forming carbon-based acids, which are corrosive to metal surfaces. They reduce the formation of varnish, gums, asphaltenes and sludge. They are used in just about every type of automotive or industrial lubricant or grease.


    These additives clean and protect metal surfaces. They help prevent harmful surface deposits and neutralize acid contaminants. They are used in engine oils, hydraulic oils, transmission fluids, metalworking fluids and greases


    Demulsifiers improve base oil properties by maintaining proper viscosity and protecting metal from the corrosive effects of water. They are used in gear oils and industrial lubricants


    Emulsifiers allow liquids that are not normally soluble to mix together, such as oil and water. They are typically used in soluble oil metalworking fluids.


    Dispersants also help protect metal surfaces. They keep soot and insoluble contaminants in stable suspension and prevent the formation of deposits, sludge and varnish. They are used in engine oils, transmission and hydraulic fluids, ear oils and industrial lubricants


    These additives reduce or eliminate the formation of foam, which can lead to poor lubrication and reduced efficiency. They provide stable oil film and cooler operating temperatures. They are used in hydraulic fluids, engine oils, transmission fluids, gear oils and industrial lubricants


    These additives help control the viscosity, or thickness, of the lubricant under different operating conditions, ensuring it maintains its lubricating properties at both low and high temperatures. They improve base oil properties


    These additives reduce friction between moving parts, reducing the amount of energy needed and increasing efficiency


    These additives protect metal surfaces from rust and corrosion caused by moisture and other contaminants. They are used in engine oils, transmission and hydraulic fluids, gear oils, grease, fuel improvers and industrial lubricants.


    These additives are used in applications where high pressures and loads are present, such as in gearboxes. They provide additional protection by forming a lubricating film under extreme pressure conditions. They are used in gear oils, greases and many industrial lubricants.


    These additives promote adhesion of lubricant to the metal surface and promote cohesion within the lubricant. They are used in grease, gear oils and industrial lubricants.



Thickeners are molecules, polymers or particles that are partially soluble in a lubricant. The main thickener types are simple soaps,  complex thickeners and non-soap thickeners

Simple Soap Thickeners

These thickeners tend to break down at higher temperatures and don’t shear as well as complex soaps.


    • Lithium Stearate
    • Lithium 12-hydroxysterate
    • Calcium anhydrous
    • Calcium hydrated (cup grease)
    • Aluminum
    • Barium
    • Sodium


Lithium 12-hydroxystearate

Complex Thickeners

These thickeners are more shear stable and resistant to high temperature breakdown than simple soaps.



    • Lithium Complex
    • Aluminum Complex
    • Calcium Complex




Lithium Complex

Non-Soap Thickeners

These thickeners are used mostly for highly specified lubricants that may require additional properties.


    • Calcium Sulfonate
    • Calcium Sulfonate Complex
    • Polyurea (Good oxidative stability, sealed-for-life applications)
    • Clay (Good for very high temp applications w/ no dropping point)





Calcium Sulfonate

Refining process 

  1. Atmospheric Distillation
    • Used to separate fuel from the crude oil, the products are known as distillates.
  2. Vacuum Distillation
    • Used to distill and separate heavier elements that would be damaged during atmospheric distillation. This process is used to obtain the base oil viscosity and flash point, it also provides the four distillates that finished petroleum products are made from.
  3. Refining
    • This process removes unwanted chemicals from the base oil to improve its characteristics. There are two main types of refining:
      1. Solvent Extraction: this method extracts any undesirable components from the distillates via a liquid extraction. After solvent extraction, the leftover materials are de-waxed and hydrofinished to improve their color and stability.
      2. Catalytic Hydrogenation/Hydrotreating: this subjects distillates to a chemical reaction with hydrogen in the presence of a catalyst. This reaction takes place at extremely high temperatures and pressure. This is the favored method of many modern refineries because of the superior quality of the produced base oil and lack of waste.
  4. De-asphalting
    • This step removes any heavy asphalt residue that may impact a distillates quality.
  5. De-waxing
    • This step is performed to reduce the wax content of a base oil to further improve its low-temperature properties.
  6. Blending
    • The final step in the process is creating a finished lubricant by blending different base oils and additives to obtain the specified viscosity and properties


A pared down version of the refining process is as follows:

Important Vocabulary to Remember:
  • Hydrofinishing: the mild process that removes remaining traces of undesirable compounds.
  • Hydrotreating: this is a refining hydrogenation carried out to improve color, odor, oxidation stability and demulsifying properties of distillates.
  • High-pressure Hydrogenation: also known as “hydrocracking”, this process completely removes unwanted compounds and can convert other elements into more desirable forms.