Additive Depletion and How it Occurs

Lubricants are essential for the efficient operation of all machinery, to reduce friction, wear, and corrosion while ensuring smooth performance.

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These lubricants are made up of base oil and a package of additives. The base oil provides the most fundamental role of a lubricant via the viscosity to form a lubricant film that separates relative moving surfaces. Depending on the application, different additives are carefully selected to enhance lubricant performance. Each additive will either:

• Enhance a desirable property of the base oil

• Suppress an undesirable property of the base oil or

• Add a new property of which that base oil does not provide

These additives include oxidants inhibitors, corrosion inhibitors, viscosity index improvers, foam inhibitors, anti-wear additives, detergents, and more. Each serves a core function, typically indicated by its name. However, while each additive implies an ability to “inhibit” oxidation or “improve” the viscosity index, this ability is not unlimited and does not exist without a need for caution. Over time, additives are exposed to conditions which cause them to diminish their ability, or more simply, to deplete. Often, it’s the core purpose of the additive that can become its demise.

The Role of Additives in Lubricants

Additives are crucial in extending the life and performance of lubricants. Their functions are broadly categorized into three groups:

• Enhancing Properties: For instance, viscosity index improvers enhance the viscosity stability of the lubricant across a range of temperatures.

• Suppressing Undesirable Properties: Each oil has a pour point, which is the temperature at which the lubricant begins to solidify. This undesirable property is suppressed by pour point depressants helping maintain the oil's fluidity down to a lower temperature.