Tagged: viscosity

What are some innovations and future trends of Viscosity Index Improvers?

Innovations in Viscosity Index Improvers

As per Mortier, Fox, & Orszulik (2010), the three most important commercial VII families represent critical commercial techniques for manufacturing high molecular weight polymers. These are polymethacrylates produced by free radical chemistry, olefin copolymers produced by Ziegler chemistry, and hydrogenated styrene-diene or copolymers produced by anionic polymerization. While they are critical, these formulations will not be discussed in detail in this article, but we will take a look at some of the innovations within this space.

PARATONE®a, a family of viscosity index improvers currently belonging to Chevron Oronite, boasts of having developed the first Olefin Copolymer VII (Mid Continental Chemical Company Inc, 2024). However, upon further investigation, it must be noted that Exxon Chemicals was the original developer behind this product. Back in 1998, Oronite Additives, a division of Chevron Chemical Co. LLC, acquired the assets of Exxon Chemical’s Paratone crankcase olefin copolymer (OCP) Viscosity Index Improver Business (Chevron Chemical Co. LLC, 1988).

This particular Viscosity Index Improver has seen developments since the 1970s and offers solid and liquid VIIs for companies to include in their formulations (Chevron Oronite, 2024). It also allows improved formulating flexibility for developers, which can significantly reduce the costs involved or specialized base stocks depending on the product to be made. This is just one company that specializes in producing VIIs for the wider global market.

There are many other companies that have innovated in the Viscosity Index Improver space, but most of this work is patented as it involves heavy-balanced formulations. Other companies have also innovated on the production side of the VIIs by engineering equipment that can help produce a higher-quality VII.

Future Trends

(Future Market Insights, 2024) estimates the Viscosity Index Improver market will be USD 4.06B in 2024 and will increase to USD 5.39B by 2034. Additionally, in 2024, vehicle lubricants account for around 51.6% of the VII market. This is not just limited to the multigrade oils but includes transmission fluids, greases, and other oils. On the other hand, with the move towards more sustainable oils, Ethylene propylene Copolymer (OCP) is projected at a 30.4% industry share in 2024. Given the move towards more sustainable products, this is expected to increase.

If we take a global view of the compound annual growth rate (CAGR) per country to 2034, we can find some interesting facts. The United States shows a CAGR of 1.6%, with a heavy allocation towards more vehicle engine oil use and the manufacturing sector for pharmaceuticals and chemicals. On the other hand, Spain is projected to see a CAGR of 2.2% with auto manufacturers and power generation equipment (hydraulic oils, turbine oils, and greases).

Venturing to China, they have a CAGR of 3.2% due to the increased number of vehicles and significant industrialization. Their involvement in complex machinery will also drive this growth. The United Kingdom is positioned to see a CAGR of 1.1% resulting from its rise in high-performance engines and heavy industrialization. On the other hand, India should experience a CAGR of 4.3% with its high demand for industrial production, commerce, and automobiles.

Figure 2: CAGR% per country to 2034

With these positive CAGRs, it is conclusive that there will be a lot of growth within the VII industry. (Future Market Insights, 2024) also list some of the recent developments in the VII Market, which include:
In July 2023, Chevron Phillips Chemical announced a capacity expansion of its VII productions to meet the increasing demand for VIIs in the automotive and industrial sectors.
In April 2023, Lubrizol introduced a new line of viscosity index improvers (VIIs) for automotive lubricants, claiming to offer enhanced performance, including improved oxidation and thermal stability.
In March 2023, ABB completed the Marunda 2.0 oil blending plant extension project, doubling production capacity within three years despite challenges during the pandemic.
In October 2022, LCY Chemical Corp., a Taiwanese material science company, showcased its thermoplastic elastomer portfolio at K 2022. It highlighted its innovative approach to material science for a sustainable future, backed by a global distribution network.
In August 2022, Evonik’s Oil Additives division in CIS countries partnered with ADCO to enhance the energy productivity and effectiveness of industrial lubricants for construction, agriculture, mining, and manufacturing equipment.

From this, the future of Viscosity Index Improvers can only be enhanced by several of the major key players expanding their operations and innovating their creations to adapt to ever-evolving standards/guidelines set by OEMs and governments. As new regulations emerge regarding improved efficiency, increased oxidation stability, and thermal stability for lubricants, VII developers will be challenged to innovate new solutions for the lubricants to conform.

References

Chevron Chemical Co. LLC. (1988, October 08). Oronite Additives Acquires Exxon’s Paratone Viscosity Improver. Retrieved from Pharmaceutical Online: https://www.pharmaceuticalonline.com/doc/oronite-additives-acquires-exxons-paratone-vi-0001

Chevron Oronite. (2024, June 29). PARATONE® viscosity modifiers. Retrieved from Oronite: https://www.oronite.com/products-technology/paratone-products.html

Future Market Insights. (2024, April 15). Viscosity Index Improver Market Forecast by Vehicle and Industrial Lubricant for 2024 to 2034. Retrieved from Future Market Insights: https://www.futuremarketinsights.com/reports/viscosity-index-improvers-market

Gresham, R. M., & Totten, G. E. (2006). Lubrication and Maintenance of Industrial Machinery – Best Practices and Reliability. Boca Raton: CRC Press.

Mid Continental Chemical Company Inc. (2024, June 29). Viscosity Modifiers / Viscosity Improvers. Retrieved from Mid-Continental Chemical Company: https://www.mcchemical.com/lubricant-additives/viscosity-index-improvers

Mortier, R. M., Fox, M. F., & Orszulik, S. T. (2010). Chemistry and Technology of Lubricants – Third Edition. Dordrecht: Springer.

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Oil Properties

What impact do Viscosity Index Improvers have on Efficiency, Wear, and Degradation?

If we filled a swimming pool with honey during the winter when no heating was available, the honey would crystallize and become more viscous. Hence, if anyone tried to walk through the pool, moving would be difficult and require more energy. However, if heating was available to the pool, then the honey would be more fluid, and someone could walk a bit more freely (although still sticky at the end of the day!). As such, they would not have to exert as much energy.

The same applies to lubricants and their viscosities. If the lubricant is too viscous (thick honey in the winter), then more energy is required for the components while they are moving. For systems with varying temperatures, finding a lubricant that can maintain the desired viscosity for those changes is challenging.

However, with the invention of Viscosity index improvers, oils can now maintain a desired viscosity at variable temperatures. This significantly affects the energy the system requires and can reduce the energy needed, making some systems more efficient.

As such, the system’s overall efficiency is impacted, and less energy is required to overcome the internal frictional forces of the lubricant (as its viscosity remains within the required range). Passenger car engine oils saw this change with the integration of VIIs when multigrade oils were invented. They no longer needed one oil for summer and another oil for winter. This significantly saved many owners from draining and replacing their oils seasonally or finding their oil frozen in the winter!

Viscosity index improvers, therefore, enhance the overall efficiency of these systems by maintaining the lubricant’s viscosity throughout the changing temperatures. Subsequently, there is no need for additional heaters in the lube oil system, which would also require additional energy. This is another area where cost and energy savings can also be achieved.

Maintaining a particular viscosity at variable temperatures allows the lubricant to form a full film (also known as hydrodynamic or elastohydrodynamic lubrication) between the two surfaces, thus offering them protection from wear.

If the viscosity became reduced (due to an increase in temperature without the VII), then the lubricant would not form a full film or experience boundary or mixed lubrication. In this case, there is the potential for increased wear, which will negatively impact the components in the system. As such, using VIIs can also reduce the potential occurrence of wear or aid in reducing wear.

As per (Gresham & Totten, 2006), this does not mean that the viscosity never changes. When the viscosity of a lubricant changes, its viscosity index will change accordingly. If the viscosity index decreases, this can likely be because of the breakage of the polymeric Viscosity Index Improver polymer molecules to produce smaller chains, which essentially reduce its originally intended effect. If there is a reduction in the molecular weight of the VII, then the lubricant will see a reduced viscosity at both 40 & 100°C. This also reduces the temperature related viscosity effect.

Viscosity Index Improvers significantly improve a system’s overall efficiency and can help reduce wear. However, these additives can degrade over time with high temperatures and shear stress.

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Oil Properties

What is the role of Viscosity Index Improvers in Lubricants?

Viscosity Index Improvers began their commercial debut around the 1950s to accommodate the new developments in automotive oils, which were then adapting multigrade viscosities. However, they were used even before (back in the 1930s) when workers in crude distillation realized that small amounts of rubber improved the VI of the oil but also increased sludge formation.

Today, VIIs are still primarily used as engine lubricants. They can also be found in automatic transmission fluids, multipurpose tractor transmission fluids, power steering fluids, shock absorber fluids, hydraulic fluids, manual transmission fluids, rear axle lubricants, industrial gear oils, turbine engine oils, and aircraft piston engine oils. (Mortier, Fox, & Orszulik, 2010)

Essentially, VIIs try to maintain the oil’s viscosity at varying temperatures. They try to ensure that the oil does not experience a loss of viscosity, which can occur due to high temperature or shear. VIIs can be considered polymers, which are tightly wound coils. When temperature or shear is applied to these coils, they unravel (lose their viscosity). Depending on the amount of shear, they may never recover their original shape (or viscosity).

As seen in Figure 1 below, Mortier, Fox, & Orszulik (2010) describe the change in the shape of the VIIs as a result of high temperature or shear. They can coil and uncoil depending on the shear stress, but if the bonds are broken, they will not reform their original coil and lose their intended viscosity.

Figure 1: Mechanical Polymer Degradation (excerpted from (Mortier, Fox, & Orszulik, 2010)

Interestingly enough, it must be noted that some VIIs provide lubricants with additional functions of Pour point depression and dispersancy. This is highly dependent on their composition.

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Oil Properties

What are Viscosity Index Improvers?

Viscosity Index Improvers (VIIs) are additives that help maintain the viscosity of lubricating oils across a wide temperature range, ensuring consistent performance.

This article will explore the nature of viscosity index improvers and their role in industrial and automotive lubricants. We will also look at their impact on lubricant efficiency, innovations involving this type of additive, and future trends.

Before discussing the nature of viscosity index improvers, we need to understand the role of viscosity. Essentially, this is one of the most critical functions of a lubricant, as it directly affects its flow rate and ability to keep the two interacting surfaces apart.

By nature, all base oils have an assigned viscosity based on their blend. However, other properties are required when we’re creating finished industrial or automotive lubricants. For instance, we may need the oil to withstand higher temperatures while still maintaining a particular viscosity, which not only provides wear protection for the equipment but also flows at a rate that does not incur frictional losses. Those are a lot of functions!

Typically, as temperature increases, viscosity decreases, and as the temperature decreases, the viscosity increases. One example is the state of water: when heated, it can turn into a gas (lower viscosity), or when frozen, it can transform into ice (higher viscosity). However, depending on the type of material, there will be varying rates of viscosity change with temperature. The viscosity/temperature relationship is called the viscosity index (VI).

As per Mortier, Fox, & Orszulik (2010), the kinematic viscosity of oil is measured at 40°C and then at 100°C. The viscosity change is then compared with an empirical reference scale initially based on two sets of crude oils: a Pennsylvania crude arbitrarily assigned a VI of 100 and a Texas Gulf crude assigned a VI of 0.

The higher the VI, the less effect that temperature has on the oil, which means that the oil can maintain a particular viscosity for a longer time at a more extensive temperature range. This is ideal for lubricants in environments experiencing temperature changes. However, not all oils have a high viscosity index. Typically, paraffinic oils can have a very high viscosity index. On the other hand, naphthenic oils have a low or medium viscosity index. The table below gives an overview of the viscosity index for various oils.

Table 1: Viscosity index of API Groups I-III

When trying to manage or alter the viscosity index of the oils above, the use of Viscosity Index Improvers (VII) can help by adding that property to an oil to allow it to have other beneficial properties. As per (Mortier, Fox, & Orszulik, 2010), viscosity index improvers consist of five main classes of polymers:

Polymethylmethacrylates (PMAs).
Olefin copolymers (OCPs).
Hydrogenated poly (styrene-co-butadiene or isoprene) (HSD/SIP/HRIs).
Esterified polystyrene-co-maleic anhydride (SPEs)
A combination of PMA/OCP systems.

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Oil Properties

Measuring Oil Viscosity

The viscosity of oil is one of its most essential characteristics. Thus, it is important to understand how this is measured and quantified. There are two main types of viscosity, dynamic (or absolute) and kinematic viscosity.

The dynamic viscosity measures the force required to overcome fluid friction in a film and is reported in centipoise (cP) or in SI units Pascal Seconds (Pa s) where 1 Pa s = 10 P (Poise). It can also be considered the internal friction of a fluid. This is usually used for calculating elastohydrodynamic lubrication related to rolling element bearings and gears.

On the other hand, the kinematic viscosity of a fluid is the relative flow of a fluid under the influence of gravity. Its unit of measure is centistokes (cSt) which in SI units is mm2/s, 1cSt = 1 mm2/s. (Mang & Dresel, 2007).

Kinematic Viscosity = Dynamic Viscosity / Density

Other units of measure for viscosity include; Saybolt, Redwood, and Engler, but these are less widely used than the cSt or cP, especially for lubricants.

Oil Viscosity Grades and Standards

One of the best-kept secrets about viscosity is that a particular grade often represents a range. When oils are classified, one may see an ISO 32 or ISO 220 and believe that the oil will have this exact viscosity (32 cSt or 220 cSt). However, this is not the case.

There are three general classifications where viscosity grades have particular ranges based on the fluid type. The fluid may behave differently in each application, hence the need for these three scales. However, there is a chart that allows users to convert the various scales into the one needed.

Engine Oil Classification (SAE J300)

As per the Society of Automotive Engineers (SAE), the SAE J300 standard classifies oils for use in automotive engines by viscosities determined at low shear rates and high temperature (100°C), high shear rate and high temperature (150°C) and both low and high shear rates at low temperature (-5°C to -40°C) (Pirro, Webster, & Daschner, 2016).

Engine manufacturers have widely used this system to aid in designing lubricants suited for these applications. As such, oil formulators also adhere to these classifications when engineering lubricants.

One will note the use of the suffix letter “W” in some of the grades below. These oils are intended for low ambient conditions, whereas those without the “W” are intended for oils that will not encounter low ambient conditions.

These are commonly described as multigrade (where the “W” is found between two numbers) and monograde oils (where the “W” is at the end or the grade is identified by a number only) in the table below.

The table shows that the viscosities must fall within a particular range to be classified. For instance, a 5W30 oil should meet the specifications of:

Low temperature, Cranking viscosity of 6600 cP at -30°C
Low temperature, Pumping Viscosity Max with No Yield Stress of 60,000 cP at -35°C
Low shear rate Kinematic viscosity at 100°C should be between 9.3 -12.5 cSt
High Shear rate viscosity at 150°C Max at 2.9 cP

One will notice the range of 9.3 to 12.5 cSt (at 100°C). This is where oils can be blended to either end of this scale but still achieve the classification of a 5w30 oil.

Axle and Manual Transmission Lubricant Viscosity Classification (SAE J306)

As per the SAE recommended practice J306, automotive manual transmissions and drive axles are classified by viscosity, measured at 100°C (212°F), and by the maximum temperature at which they reach the viscosity of 150,000 cP (150 Pa s) when cooled and measured in accordance to ASTM D2983 (Method of Test for Apparent Viscosity at Low Temperature Using Brookfield Viscometer). (Pirro, Webster, & Daschner, 2016).

The table below shows that for an SAE grade of 190, the kinematic viscosity must fall within the range of 13.5 to 18.5 cSt at 100°C. While most viscosities tend to fall mid-range of these values, it also indicates that if the lubricant achieves 18 cSt at 100°C, it can still be classified at an SAE grade 90.

The most common multigrade lubricants within this grade fall within the 80w90 or 75w140 classifications.

Another factor for these types of lubricants is API GL4 or GL5 ratings. It must be noted that a GL5 lubricant is recommended for hypoid gears operating under high-speed, high-load conditions.

On the other hand, a GL4 lubricant is usually recommended for the helical and spur gears in manual transmissions and transaxles operating under moderate speeds or loads. These should not be used interchangeably as the GL5 lubricants tend to adhere to the surfaces and may cause more damage in a GL4 application.

Figure 5: Automotive Gear Lubricant Viscosity Classification. Source: Lubrication Fundamentals, Third Edition Revised and Expanded by Pirro D. M., Webster M., and Daschner E. pg 52

Viscosity System for Industrial Fluid Lubricants

This classification was jointly developed by the ASTM and STLE (Society for Tribologists and Lubrication Engineers). Initially, the system was based on viscosities measured at 100°F but converted to viscosities measured at 40°C.

ASTM D2422 and ISO 3448 are the references for this system. In this system, it is clearer to see the variances in the ranges of viscosities. In this case, the mid-point of the range is used as the ISO viscosity. To determine the range of any ISO viscosity, one can calculate ±10% of the mid-point value to get the minimum and maximum values of the range.

Figure 6: Viscosity System for Industrial Fluid Lubricants. Source: Lubrication Fundamentals, Third Edition Revised and Expanded by Pirro D. M., Webster M., and Daschner E. pg 52

All of these systems can be represented in the figure below, where it is easy to calculate the oil viscosity using another system:

Figure 7: Various viscosity systems in one chart.

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Oil Properties

Factors That Affect Oil Viscosity

Similar to the molasses and water examples above, different factors can affect the viscosity of a liquid. For instance, water can assume other states depending on the temperature.

If water is at its freezing point (0°C), it can turn to ice but remains liquid at room temperature (around 20-30°C). Then, at 100°C, it can turn into a vapor. Its viscosity can change depending on the influencing factors.

Four factors affect oil viscosity:

Temperature
Pressure
Shear rate
Oil type, composition, and additives

Temperature

As seen with the example of the water above, when the temperature decreases, the water can turn to ice. Similarly, for lubricants, as the temperature drops, the viscosity increases. This means the oil will get thicker or more resistant to flow at lower temperatures. Likewise, as the oil heats up, it can become thinner.

This is similar to a block of ice melting as temperatures increase. Its viscosity will decrease, and the ice will turn to water. In this case, the internal molecules gain more energy with the increase in temperature, lowering the internal friction within the fluid. As such, the viscosity also decreases.

Since the oil’s viscosity will change with temperature, most OEMs will supply a temperature–viscosity chart for their equipment to help ensure the correct viscosity is used depending on the operating temperature.

In the figure below, gear oils of varying viscosities are plotted against the temperature for a particular piece of equipment. OEMs will typically specify the optimum operational viscosity range for their equipment.

It is then up to the lubrication engineers to determine the ideal viscosity based on the conditions of their equipment (this can vary depending on the application).

Figure 1: Temperature – Viscosity chart for Shell Omala S2 G (Source: Shell Lubricants TDS)

From the figure above, one can see that at 40°C, most of the gear oil grades correspond with their viscosities (ISO 68 corresponds with a 68 viscosity). However, at 0°C, an ISO 68 gear oil can become 1000 cSt, while at 90°C, this same grade of oil is around 11cSt.

Interestingly, all of the oils listed here can achieve a viscosity of 100cSt but at different temperatures, as shown below:

32°C – ISO 68
40°C – ISO 100
47°C – ISO 150
55°C – ISO 220
63°C – ISO 320
68°C – ISO 460
75°C – ISO 680

Temperature is a significant influencing factor of viscosity, but it is not the only factor.

Pressure

The effects of pressure on a lubricant’s viscosity are often overlooked. However, the viscosity-pressure behavior has become part of the calculation for elastohydrodynamic films. In these cases, oil viscosity can rapidly increase with pressure.

One such instance occurs with metal-forming lubricants, which are subjected to high pressures such that the oil’s viscosity can increase tenfold (Mang & Dresel, 2007). As the pressure increases, viscosity also increases, protecting the surface in these lubricant films.

The very definition of viscosity alludes to pressure’s impact on Newtonian and non-Newtonian fluids. For example, with Newtonian fluids (regular lubricating oils), the shear rate is proportional to the applied shear stress (pressure) at any given temperature.

As seen above, the viscosity can be determined once the temperature remains the same. However, Non-Newtonian fluids, such as greases, only flow once a shear stress exceeding the yield point is applied (Pirro, Webster, & Daschner, 2016).

Hence, this is why the observed viscosity of grease is called its apparent viscosity and should always be reported at a specific temperature and flow rate.

Shear Rate

For Newtonian fluids, viscosity does not vary with shear rate (Pirro, Webster, & Daschner, 2016). In fact, per the definition of viscosity for Newtonian fluids (regular lubricating oils), viscosity is a constant proportionality factor between the shear force and shear rate. Thus, even when subjected to greater shear forces, the viscosity will not change for Newtonian fluids.

On the other hand, for non-Newtonian fluids, the viscosity is influenced by the shear rate. Some non-Newtonian fluids can include; pseudoplastic fluids, dilatant fluids, and a Bingham solid, the effects of shear rate on these fluids are shown in the figure below.

A Bingham solid is a plastic solid such as grease that only flows above a particular yield stress. It can be seen that pseudoplastic fluids decrease viscosity with an increasing shear rate, while dilatant fluids show an increase in viscosity with an increasing shear rate. (Hamrock, Schmid, & Jacobson, 2004)

Figure 2: Characteristics of different fluids as a function of shear rate vs. viscosity (a) and shear rate vs. shear stress (b). Source: Fundamentals of Fluid Film Lubrication by Hamrock, Schmid & Jacobson, page 102.

The shear of a lubricant can influence its shear rate. Typically, longer-chain polymer viscosity index improvers can shear over time. When this happens, it can result in a decrease in oil viscosity. Similarly, non-Newtonian fluids, such as grease, experience a decrease in viscosity as a function of shear rate (Totten, 2006).

Another essential characteristic to note is whether a material is thixotropic or rheopectic. For a thixotropic material, if it is placed under a continuous mechanical load over a period of time, the viscosity will appear to decrease over this time.

However, the original viscosity is restored after a specific rest period, as shown in the figure below. On the other hand, for rheopectic materials, continuous shearing causes the viscosity to increase. (Mang & Dresel, 2007).

Figure 3: Flow characteristics of a thixotropic lubricant (Source: Lubricants and Lubrication edited by Theo Mang and Wilfried Dresel, page 30)

Oil Type, Composition, and Additives

Various oil types, compositions, and additives can influence a lubricant’s viscosity. For instance, the five groups of base oils all have varying characteristics, as shown in the figure below. One can note the differing viscosities for the various groups.

Figure 4: Base Stock property comparison (Source: Lubricants and Lubrication edited by Theo Mang and Wilfried Dresel, page 13)

When a finished lubricant is made, it usually consists of a base oil and additives. Hence, the base oil will have a significant role in determining the final viscosity of the oil. However, with the advent of Viscosity Index Improvers, desired viscosities can be engineered regardless of the base oil type being used.

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Oil Properties

What is Oil Viscosity?

Oil viscosity is the internal friction within an oil that resists its flow. It measures the oil’s resistance to flow and is one of the most important factors in lubricants. Viscosity is also defined as the ratio of shear stress (pressure) to shear rate (flow rate).

Understanding Oil Viscosity

Imagine walking through a swimming pool filled with water. While walking through the pool, your body experiences some resistance from the water. Now imagine walking through the same swimming pool, filled with molasses this time!

It takes someone much longer to wade through a molasses-filled pool than one filled with water. In this case, the molasses is more viscous than the water. Thus, it has a higher viscosity than water.

You can also apply this to using a straw for drinking water from a glass. Pulling the liquid from the cup will be easy using a big straw. However, getting the same liquid to the person using the straw would take longer if a thinner straw were used.

Engine Oil Analogy

We can draw this analogy to car engines over the last 30-40 years. These engines had larger clearances for the oil to flow throughout the engine. As such, most of these engines used a 50-weight (or straight 50) oil.

As the technology evolved, the size of the engines got smaller. The clearances also got smaller, and the engine oil was now required to flow faster, control the transfer of heat and contaminants and keep the engine lubricated.

A straight 50 oil could not pass through the smaller straw at the speed it should. This would be equivalent to the user using a smaller straw for drinking molasses. It could take a while!

However, if a lighter weight (or less viscous) engine oil was used (such as a 0w20 or 10w30), then this is like someone trying to drink water (0w20) with a smaller straw.

It will flow much faster than molasses (straight 50) with the same straw! The lighter-weight oil would also transfer heat and flow much faster than the heavier-weight (more viscous) oil.

Future Developments and Research in Oil Viscosity

As explained at the beginning of this article, the changes in technology (such as smaller engines) will demand more from lubricants, especially in viscosity. Thirty years ago, a 0w16 engine oil was unfathomable, but today, it is being integrated into our newer model vehicles.

Some of the concepts which will continue in the future can include:

Reducing viscosity – as seen in the examples above, with most pieces of equipment getting smaller, the need for lighter weight (lower viscosity) oils will continue as OEMs constantly evolve and push the boundaries of their equipment.
Measuring viscosity – traditionally, viscometers have always been used where the difference in the height of the liquid at particular temperatures (or under certain conditions) is measured. Given the advancements in technology, this may be subject to change very shortly into a more reliable and even more accurate method.
Viscosity-dependent parameters – temperature and pressure have the most significant impacts on the oil’s viscosity. However, some of these challenges can be overcome with the advent of viscosity index improvers. With enhancements in the formulation of viscosity index improvers, one can expect oils of varying viscosities to be used in parameters they could not have used in the past.
Alternative oils – more sustainable options are constantly being explored. Whether this lies in using plant-based oils or other alternative bio-based oils, these may introduce new ways or conditions under which different viscosities can exist.

Overall, viscosity is one of the most important characteristics of a lubricant. It can easily influence the impact of the oil on the internal surfaces of the equipment and its overall energy efficiency.

It is important to remember that oil viscosity should be determined by the application in which it is being used. Parameters such as temperature, pressure, and shear rate should all be considered when selecting the lubricant’s viscosity.

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Industrial / Strategic Tips

Mixing viscosities

Can I mix different viscosities of oils to get the viscosity that I want?

It can be done but this is not an ideal situation.

There are times when the only available viscosity is an ISO 46 (on a rig) but the equipment requires an ISO 68 and the new stock will not be delivered in time to avoid shutdown. Can the ISO 46 be used instead?

An ISO 46 oil is lighter in viscosity than an ISO 68 however, for most oils, there is a chart that depicts the viscosity of the oil at operating temperature. In these cases, one can consult this chart and determine if the viscosity at operating temperature will still fall within operating limits.

If we mix an ISO 46 with an ISO 68 oil we cannot be certain of where the new viscosity will fall especially if we do not know the ratios that are being used. There is a viscosity calculator that can help guide this decision available at: https://www.widman.biz/English/Calculators/Mixtures.html

This can be used as a guide and the actual values of the oil should be verified via oil analysis.

While this situation is not ideal, we need to remember that compatibility is also key.

As such, we should stick with the same line of lubricants that we being used. Typically, lubricant suppliers have the same formulation but change the viscosities for lubricants of the same line.

Automotive / Strategic Tips

Mixing oils

Can I mix hydraulic oils with engine oils?

Oils should never be mixed!

Every oil is designed with its application in mind. As such, they are blended with varying concentrations and types of additives. For instance, a typical engine oil has at least 30% additives while a turbine oil may have only 1% additive.

Hydraulic oils are designed for applications where power has to be transmitted through the lubricant. On the other hand, engine oils are designed to withstand varying temperatures (gasoline engines have a different temperature range compared to diesel engines. Diesel engines generally run at higher temperatures than gasoline engines).

Always pay particular attention to what the OEM recommends. Usually, the OEM will recommend that a lubricant meets a particular global standard (API SN or CK4). These standards were developed to ensure the best performance of an engine and should be adhered to when choosing lubricants.

Automotive / Strategic Tips

Multigrade vs Monograde

Why use multigrade instead of monograde oils?

A monograde oil does not provide the same level of protection on start-up as a multigrade oil.

With the multigrade oil, it is designed to reduce the time it takes to get from the bottom of the sump to the top of the engine (this is indicated by the number in front of the “w”).

However, the monograde oils have not been adapted for this type of technology. Thus, it takes longer to get to the top of the engine and to all the components compared to a multigrade oil.

Most wear occurs on start-up. Before we start the car on a morning, all of the oil is at the bottom of the sump, so it takes some time to get to the top and the other components. However, once we start the engine, all the parts will begin moving. If they are moving without any lubrication, then a significant amount of wear will occur!

Typically, when driving, we start the car, go to our destination and stop. Then come back and start the car again. During this time, the oil would have drained back to the bottom of the sump and now has to get back to the top. Before it gets to the components, these are still moving without lubrication, inducing wear! If we think of the number of times that we start and stop for the day (or for the month!), we will realize the amount of wear that we put our engines through.

Hence, this is one of the main reasons, that we choose multigrades over monogrades.