Engine lubricants are complex fluids. Today’s higher performing engine lubricants contain a carefully balanced formulation of base oils, advanced additives and viscosity modifiers, each performing very specific and vital functions.

To work as intended, each lubricant needs to be carefully formulated and tested to ensure it performs up to or beyond specific approval and performance requirements. The below gives an overview of the typical components in an engine lubricant, reinforcing the complexity involved in formulating as well as understanding the specific needs the lubricant needs to perform to.

Base Oil
Let’s start with the base oil. The American Petroleum Institute (API) has categorized base oils into five categories and within each category, base oils have a wide range of different technical and performance characteristics. And while the base oil makes up the majority of a heavy duty engine lubricant (which typically fall within 60 to 95% of the weight), even the highest quality base oil alone cannot provide full protection against the effects of heat, the forces of shearing, the effects of wear particles, chemical and water dilution as well as corrosion.

When developing additive packages, formulators need to be aware of the specific base oil being used, as different additive formulations will be required according to the characteristics of each base oil.

Viscosity Modifiers
Viscosity modifiers are polymers specifically designed to help control the viscosity (thickness) of a lubricant over a specified temperature range and operating environment. As engine components become more and more sophisticated, advanced polymers enable more efficient operation, in increasingly severe environments and are critical in providing maximum efficiency, durability and protection.

A wide range of viscosity modifier technologies exists and the specific viscosity modifier required is dependent upon a number of interrelated factors including the operating conditions the overall lubricant needs to perform in, alongside the base oil and additives being used.

Although the additives make up a small part of the volume of the lubricant, they have a big role in protecting critical engine parts. The additive package can contain:

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DETERGENT — A detergent is a substance added to a fuel or lubricant to keep engine parts clean. In motor oil formulations, the most commonly used detergents are metallic soaps with a reserve of basicity to neutralize acids formed during combustion. (Maintaining Cleanliness)
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DISPERSANT — A dispersant is an additive that suspends contaminants in the oil, preventing sludge and varnish deposits on engine parts. Usually nonmetallic (“ashless”) and used in combination with detergents. (Handling Contaminants)
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ANTIOXIDANT – An antioxidant or oxidation inhibitor is an additive, usually incorporated in a relatively small proportion, to slow the oxidation of lubricants. (Minimizing Oxidation)
Anti-wear agent
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ANTIWEAR AGENT – An antiwear agent is an additive that works within a formulation to form thin, tenacious films on highly loaded parts to prevent metal-to-metal contact. (Reducing Engine Wear)
Friction modifier
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FRICTION MODIFIER – A friction modifier is an additive that attaches to a surface and is used to reduce friction and wear when mild sliding conditions occur. Friction depends on the smoothness of the contacting surfaces, as well as the force with which they are pressed together. (Reducing Engine Wear)
Foam inhibitor
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FOAM INHIBITOR – A foam inhibitor is an additive that inhibits oil foaming in a lubricant. Foam leads to pump cavitation or loss of lubricant flow. (Decreasing Aeration)
Corrosion inhibitor
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CORROSION INHIBITOR – A corrosion inhibitor is an additive that protects lubricated metal surfaces from chemical attack by water or other contaminants. (Controlling Corrosion and Acids)
Pour point depressant
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POUR POINT DEPRESSANT – A pour point depressant is an additive used to lower the pour point or low-temperature, low shear-rate fluidity of a petroleum product.(Managing Viscosity)

All of those additives must be carefully balanced so that they work together to perform their specific functions. Lubrizol’s chemists have the expertise to create these complex formulations so that none of the additives, base oil and viscosity modifiers are in conflict with each other, and they all work in harmony so the lubricant performs as intended. Too much of one additive can prohibit the other additives and viscosity modifiers from doing their jobs. For example, if there is too little foam inhibitor, foam will form and the engine will cavitate, resulting in damage. Likewise, if the wrong type of detergents are used, the acids won’t neutralize. Dispersants won’t be able to keep the soot from agglomerating and depositing on engine parts. So, everything has to work together in precise harmony. And that’s where Lubrizol’s foundation of chemistry knowledge comes into its own. Our formulators know how to create additive packages to address everything from durability and protection requirements to fuel economy and efficiency benefits.

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