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Lubricant Basics – Lubricant Additives

Additives are combined with base stock to improve the properties of the machinery under different operating conditions and performance requirements.  There are very few unadditized mineral oils that are sold as lubricants. Most of all commercial lubricants contain some form of additives to enhance their performance, this ranging from less than 1% to 25% or more. By far the largest market for such additives is in the transportation industry, including additives for engines and drivetrains in cars, trucks locomotives, buses, and ships. The same range of additive types may be applicable in other industries for example industrial lubricantsc

To be acceptable, additives must be capable of being handed in conventional blending equipment, stable in storage, free of offensive odoursand non-toxic by normal industrial standards. Generally sold as concentrated solutions in oil because many are highly viscous materials or solids. The main function for additives is summarized as:

  • Protects the metal surfaces

  • To extend the range of lubricant applicability

  • Extends lubricant life

To be acceptable, additives must be capable of being handed in conventional blending equipment, stable in storage, free of offensive odours and non-toxic by normal industrial standards. Generally sold as concentrated solutions in oil because many are highly viscous materials or solids.

Additive Containers

Surface Protective Additives for Automotive Lubricants

Additive Type: Antiwear and EP Agent

Purpose: Reduce friction and wear and prevents scoring and seizure

Functions: Chemical reactions with metal surfaces to form a film with lower shear strength than the metal, therefore preventing metal-to-metal contact.

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Additive Type: Corrosion and Rust Inhibitor

Purpose: Prevent corrosion and rusting of metal parts in contact with the lubricant

Function: Provides protective film adsorbing onto metal surface thus blocking the effects of water, acids (neutralizes) or air.

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Additive Type: Detergent

Purpose: Keep surface free of deposits

Functions: Chemical reactions with sludge and neutralize them and keep them soluble.  

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Additive Type: Dispersant

Purpose: Keep insoluble contaminant dispersed in the lubricant

Function:  The contaminants will bond to the dispersant molecules, preventing it to form and kept in suspension

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Additive Type: Friction Modifier

Purpose: Minimizes light surface contact, such as sliding and rolling. Alters the coefficient of friction.

Function: Preferential adsorption of surface-active materials


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Performance Additives – Automotive Lubricants

Additive Type: Pour Point Depressant

Purpose: Enable lubricant to flow at low temperatures

Function: Modify wax crystal formation to reduce interlocking

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Additive Type: Seal Swell Agent

Purpose: Swells elastomeric seals, maintaining seal integrity

Function: Chemical reaction with elastomer to cause slight swell

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Additive Type: Viscosity Modifier

Purpose: Reduce the rate of viscosity change with temperature

Functions: Polymers expand with increasing temperature to counteract oil thinning

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Additive Type: Anti-foamant

Purpose: Prevent lubricant from foaming a persistent foam

Function: Reduces surface tension to speed collapse of foam

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Additive Type: Antioxidant

Purpose: designed to prolong the life of a lubricant by increasing the oxidative resistance of the base oil

Function: Decompose peroxides and terminates free-radical reactions

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Additive Type: Metal Deactivator

Purpose: Reduce catalytic effect of metals on oxidation rate

Functions: Form inactive film on metal surfaces by complexing with metallic ions

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