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Our own R&D initiatives on engine wear mechanisms and collaborations with OEMs, oil companies and academics have demonstrated that the risks associated with reducing oil viscosity on an engine can be effectively addressed with properly designed additive technology. In our view, to ensure both fuel economy and wear protection are delivered it is increasingly important to co-engineer the vehicle and lubricant systems from an early stage in their design.
This collaborative development approach becomes even more important when you consider that it is immensely challenging to get one single low viscosity formulation that fits all engine types. Our research indicates that fuel economy lubricants must be individually tailored to suit each vehicle type, something that will add significant complexity to their development.
Impact on additives
Additives will be critical to enable lubricants to function at much lower viscosities and to ensure they retain their protective properties over ever extending drain intervals. New lubricants will not only provide additional fuel economy, but also will facilitate the introduction of new engine technologies that can deliver significant increases in both fuel economy and engine performance under more extreme operating conditions.
The use of multigrades and the move to lighter viscosity grades will impact the overall demand for viscosity modifiers. Although lighter grades will require a lower treat of polymeric additives, the selection of the polymer becomes even more critical in maximizing fuel economy and delivering low temperature protection.
Going forward, looking at different combinations of viscosity modifier polymers and base stocks may help us to gain further fuel economy improvements.
How low can viscosity go? The results from one piece of work, shown in Figure 2, demonstrate that as viscosity goes down volatility increases, and although this is only one example, in our view this principle can be applied to all technologies.
Base stock challenges As low temperature viscosity is reduced and NOACK volatility limits are either maintained or even tightened the use of base stocks with lower viscosity and higher viscosity index (VI) is increasing. This means the pace at which we move to lower viscosity lubricants will also be influenced by the availability of high quality base stocks.
Right now the Group III market is long, and there should be sufficient volume to meet the demand for premium products. Current Group III should be fit for purpose to formulate SAE 0W-16 and 0W-20 viscosity grades with volatility performance in line with general industry specifications. But the introduction of ultra low viscosity oils, or lubricants with tighter volatility requirements, will require very high VI or PAO base stocks to maintain performance. It is not clear if there will be enough of these products to meet demand, which will place increasing investment challenges on all stakeholders.
This is a very complex area, where decisions are mainly driven by OEM specifications, and growth of these low viscosity grades over the next decade is hard to predict. Because OEM specifications are not all the same, the Group III, high VI Group III+, PAO, and ester base oils mix can vary depending on which characteristics in the specification are the most challenging to meet. At Infineum we believe part of our job is to provide the most cost effective and supply reliable formulation solution to the market.
A fine balance The improvement of fuel economy is undoubtedly one of the biggest drivers for change in the automotive industry, which means lowering the viscosity of engine oils is a trend that is here to stay.
But, it is clear that thorough formulation development and careful base stock selection is essential to ensure we strike the right balance between fuel economy and hardware protection and between lubricant viscosity and volatility. SAE 0W-16 oils are already in use, and we believe the technical wear protection challenges that they present can be handled by lubricant and engine design advances. But, as we have demonstrated, lubricant derived fuel economy is engine specific and involves the careful combination of appropriate base stock and additive technology in a tailored formulation.
The question that we need to help answer is how fast and how far could, and should, viscosity go? Some OEMs are already looking to go below SAE 0W-16 – and now SAE has approved the definition of SAE 0W-8 and 0W-12 the move to low viscosity grades may accelerate.
Although fragmented viscosity grades will add complexity to the market some OEMs are looking to push lubricant technology to the limits in order to maximise the fuel efficiency of their vehicles and avoid financial penalties. In our view the close collaboration of OEMs with lubricant and additive suppliers is essential to ensure that changes in the design of both hardware and lubricant systems work in harmony to deliver enhanced fuel economy performance without compromising engine durability.
The high operating temperatures of modern engines will typically cause the lighter ends of a lubricant to evaporate while in service. This effectively pushes the viscosity of the lubricant up and, as a result, any fuel economy improvement gained from the low viscosity of the oil may be lost due to an increase in friction.
Clearly the fine balance between viscosity and volatility is an important consideration that must be addressed in the design of the lubricant formulation.
Dr. Jonathan Flemming, Infineum Senior Lubricant Technologist, will explore the topics covered here in more detail in his paper at the 19th ICIS World Base Oils & Lubricants Conference in London from 19 – 20 February 2015.
LINK
www.infineum.com
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LUBE MAGAZINE NO.125 FEBRUARY 2015
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