An Inside Look at Viscosity Modifiers - Whitepaper

It is commonly known that viscosity is one of the most important characteristics when selecting which oil is best for an application. In the simplest terms, viscosity is a measure of a fluid’s resistance to flow. Consider water that flows easily compared to honey - honey is considered more “viscous,” hence its resistance to flow is greater than water’s. A key attribute of oil is the protection of moving parts from coming into contact with one another. It is important that the oil is viscous enough at high operating temperatures to maintain a proper lubricating film while flowing readily in cold climates to quickly lubricate moving parts upon start up. An oil that is too thick (viscous) or too thin can be detrimental over time to a piece of equipment or machinery.

Viscosity Index (VI) is another term that is used frequently and is found on product data sheets.  Viscosity Index is a scale used for lubricating oils that indicates the degree of change in viscosity with respect to temperature.  The higher the VI, the smaller the change in viscosity with respect to temperature.  Depending on how a finished lubricant is blended, base oil selection has an impact on a naturally high or low VI. There is also an additive available to modify the VI to ensure the oil performs well in its environment.   

A Viscosity Index Improver (also called a Viscosity Modifier) is the additive that enhances the characteristics of an oil to perform at low and high temperatures – these additives mitigate the effects of temperature on viscosity throughout the fluid’s range of operation.  Viscosity Index Improvers are primarily used in multi-viscosity engine oils, gear oils, power steering fluids, various hydraulic fluids and automatic transmission fluids. At low temperatures, viscosity modifiers contract so they do not impact the fluid viscosity. At high temperatures, these modifiers “relax” and increase in viscosity equating in a proper lubricating film.

There are varying levels of quality within viscosity modifier technology which can impact how long a lubricant will “stay-in-grade” in high stress conditions, indicated by a shear stability index. This index defines the resistance of a modifier to degrade, or shear, while under stress.  Take diesel engine oil as an example: Archer Premium Arpeco is formulated with a high quality, field-proven, shear-stable viscosity modifier that allows this multi-viscosity oil to last longer in the field.

There is truly more to oil, than just oil.  Understanding specific characteristics can help identify which product is best for your application, and an Archer sales rep can do just that. Contact your local Archer Lubricant distributor today or visit the ArcherOil.com product catalog to learn more about the Archer product line and how a careful selection of high-quality base oil and additives can impact the health of your operation.