Base Stocks

How Low Can You Go?


How Low Can You Go?
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Base Oil Report: Trends

As governments worldwide pass stricter standards to combat carbon dioxide emissions, lubricant formulators have been tasked with creating lubricants to meet these new standards.  

Better fuel economy, energy efficiency and durability are a necessity in the evolving marketplace. The race to make lower-viscosity fluids is on.

The fight to lower global emissions has affected the lubricants industry and will continue to. Oil majors—whose lubricant sales make up a significant chunk of the world’s demand—have vowed to reduce their carbon footprints in response to government regulations, which are becoming more urgent. 

India’s government recently enacted a new set of its own standards, jumping straight from Bharat Stage IV standards to Bharat Stage VI standards in 2020. The sale and registration of vehicles conforming only to Stage IV was banned by the country’s Supreme Court. 

In the European Union, a set of initiatives known as the European Green Deal aims to make the continent carbon neutral by 2050. These initiatives will shape the Euro 7 emissions standards, the details of which have yet to be announced but are expected to be implemented by 2025. 

Original equipment manufacturers are already facing big penalties if they fail to comply with targets set by the EU, according to Michael Sheehan, senior staff chemist at ExxonMobil Chemical Co. “The fines could amount to billions of dollars in 2021,” he said.

“The most dominant global trend in the transportation industry is fuel efficiency,” he said. “Many of the largest global economies have made great strides over the years in reducing emissions.”

The onus is on OEMs for their vehicles to comply with these more stringent standards. “Car manufacturers are under constant pressure to improve the energy efficiency and fuel economy of their vehicles,” said Nathan Vogt, global market development adviser at ExxonMobil Chemical. “Ultra-low-viscosity engine oils and electric vehicle driveline fluids are effective ways to help achieve those goals.” 

Low-viscosity engine oils help meet these emission standards by reducing oil consumption, improving oxidative stability for longer drain intervals and enhancing lubricity for better energy efficiency.

“To meet increasingly demanding OEM specifications, engine oils and EV driveline fluids need to continuously evolve to be lower in viscosity while still delivering the same or higher levels of performance and wear protection of their predecessors,” Vogt said.

Sheehan pointed to an Infineum study from 2019 that found that SAE 5W-30 grades made up a little over half the North American passenger car motor oil market that year. But these products will slowly cede their share, the company estimated, with SAE 0W-20 oils expected to be the leading product in 2024 and account for around half the market by 2029. 

“The use of 0W products is being driven by automakers, who have designed their engines to use such fluids to improve fuel economy,” Sheehan said. Some OEMs, he continued, are still trending toward even lower-viscosity products from SAE 0W-16 down to SAE 0W-8.

To accommodate the formulation of low-viscosity engine oils, lube companies have worked to develop new base stocks. For instance, ExxonMobil recently released its SpectraSyn MaX polyalphaolefin base stock, which is specifically designed for use in low-viscosity oils. It claims that 0W-12 and 0W-8 motor oils formulated with the new base stock outperformed those blended with competing base stocks in fuel economy, durability and cleanliness.

“While the trend toward lower-viscosity grades has created some challenges for formulators, SpectraSyn MaX provides formulators with more formulation flexibility than existing low-viscosity base oils, allowing for the inclusion of additives—such as viscosity modifiers for improved fuel economy, detergents or dispersants for cleaner engines, and sulfur and phosphorous for better wear protection— without compromising performance,” the company said.

ExxonMobil offers a SpectraSyn MaX 3.5 version of its product that achieves 3.51 centiStokes at 100 degrees Celsius using the ASTM D445 test method. Its 3.6 version of the product achieves 3.6 cSt at 100°C. 

In tests comparing its new offerings to a handful of other base stocks, the company tested another PAO at 4.1 cSt, two different API Group III+ base stocks at 4.16 cSt and 4.11 cSt, and a Group II product at 2.74 cSt. SpectraSyn MaX 3.5 had the lowest Noack volatility of the bunch with 11.6% weight loss and a pour point of -78°C. Ringing in at 790 centiPoise in a cold-cranking simulator test at -35°C, SpectraSyn MaX 3.5 boasted the second lowest viscosity of the bunch. In an oxidation test, the new base stock lasted 102 minutes, more than twice the length of any other product. Its flash point of 234°C also topped the other samples.  

Casting an eye toward another major industry trend, ExxonMobil says these lower-viscosity base stocks benefit electric vehicles as a “single-fluid solution.” Low-viscosity EV driveline fluids lead to increased energy efficiency and fuel economy, providing longer driving range for both hybrid and fully electric vehicles. Low-viscosity base stocks can also provide better thermal management than Group III products.

Sheehan expects internal combustion engine applications to linger for the next 20 to 30 years, even as the EV market expands. With low-viscosity products set to take over both the ICE and EV markets—and as regulations become increasingly stringent—the industry can expect to see more companies touting lower-viscosity offerings. 

Many of the world’s largest economies “have set aggressive emissions targets for the future,” Sheehan said. “We believe that low-viscosity fluids can enable the development of next-generation lubricants to meet these targets and reduce emissions.”   

Will Beverina is assistant editor for Lubes’n’Greases. Contact him at