Group III: The Big Rigs’ Next Big Thing?

As environmental regulations and stricter fuel economy mandates continue to stack on truck manufacturers, API Group III base oils are increasingly catching the attention of heavy-duty diesel engine oil formulators to bring high-performance finished lubes to fleet operators.

Speaking at the ICIS Pan American Base Oils and Lubricants Conference in Jersey City, New Jersey, Mike Brown, vice president of technology at SK Lubricants North America, said original equipment manufacturers have been designing engines to use oils containing less sulfated ash, phosphorus and sulfur (commonly known as SAPS) to safeguard their emissions handling systems, leading to more recommendations for higher performing synthetic HDEOs in their engines.

Citing ExxonMobils Global Energy Outlook to 2040, Brown mentioned that the global fleet of passenger cars and trucks is expected to rise from 800 million vehicles to 1.7 billion by 2040. In the commercial transportation sector, heavy-duty road transport is slated to consume the most energy-more than rail, aviation and marine combined-and to average 5 percent growth per year.

The transport sector faces a paradox, Brown noted in his Dec. 1 presentation. Increasing demand for fuels as a consequence of growing GDP, stacked against the target to reduce global carbon dioxide emissions.

Engine oil formulators are getting the hint, tapping into a base oil market that is becoming replete with Group III. The share of worldwide capacity for this category of base oils was calculated at 13 percent in 2016, up from 5 percent 10 years ago, according to LubesnGreases Lubricants Industry Factbook. Brown stated that 12.4 million barrels of base oils were imported into the United States in 2015, estimating 8 million of those were Group III, and they came from South Korea, Qatar, Bahrain and Canada.

These base stocks [are already used] to formulate semi-synthetics and full synthetics, and we deem that there is really no supply issue for Group III base stocks used in heavy duty oils, he added.

Brown said that the lower amount of aromatics and higher isoparaffin content in Group III give engine oils a better low temperature oil flow compared to those formulated with Group II. The higher isoparaffin content also gives higher viscosity index and lower volatility losses than Group II.

Group III also has a higher purity compared to Group II. Therefore, base oils stay out of the way and the additives in the formulation can do their job of controlling oil oxidation, deposit formation, suspending the by-products of combustion or soot, as well as lubricating critical engine components without corrosive contributions from base stock sulfur and aromatic derivatives, he elaborated.

Many OEMs are now factory-filling their trucks using fuel-saving engine oils blended from Group III base oil. European companies like Volvo, Scania, MAN, Renault Trucks and Mercedes Benz (Daimler) favor both fully synthetic SAE 5W-30 and semi-synthetic 10W-30 viscosity oils, while U.S. heavyweights such as Daimler Trucks North America, Cummins, Mack and Navistar prefer 10W-30 for initial fill.

These factory-fill products are typically very high additive treats, in the range of 17 to 21 percent and higher, Brown noted, adding that these low-viscosity range oils have been shown to benefit fuel economy and reduce emissions in field and engines tests.

Photo: iStock/vitpho

In North America, OEMs are moving away from SAE 15W-40 oils and favoring the lighter viscosity 10W-30. While off-highway operators and equipment builders will be more reluctant to give up their 15W-40, Brown predicted that on-highway fleets of trucks and light diesel pickups will see more use of 10W-30 oils, including semi-synthetics, by 2024.

Based on data from Infineum, Brown projected that SAE 10W-30, including products meeting API CJ-4 and the new API CK-4 category, will make up 25 percent of the North American HDEO market in 2021. Products like full-synthetic 5W-30 and 5W-40, on the other hand, will see minimal growth over that time range, while 15W-40s may still hold a 60 percent share.

Even though full-synthetics are a premium lubricant and carry a lot of OEM specifications, they are still a small share of the market in North America, with 4 percent combined current market share, said Brown.

While that market inches along, Group III base stocks have one advantage that blenders can take advantage of right now, Brown stressed: It allows products to be differentiated with a claim of being semi-synthetic. He pointed to tests showing that fully formulated, semi-synthetic 15W-40 engine oils made with at least 20 to 30 percent Group III can deliver meaningful benefits, such as fewer deposits and faster oil flow in low temperature conditions.

The performance boost is also seen in semi-synthetic SAE 10W-30s. In tests at Afton Chemical, Brown explained, a 10W-30 formulated with 30 percent Group III demonstrated better cold-cranking viscosity and lower kinematic viscosity for warmup than one made with only 10 percent Group III. The former also had Noack volatility losses of only 10.4 percent, versus a 12.9 percent for the latter.

Boosting Group III content to 30 percent also lifted the 10W-30s results in the difficult Volvo T-13 test, which appreciates higher quality base oil, Brown said. The 30 percent Group III product showed better kinematic viscosity control, delayed the onset of oil oxidation, and did a better job of protecting against lead-bearing wear, than the 10 percent solution.

However, he conceded, it is common practice for many blenders to use only 10 percent Group III in their semi-synthetics, so consumers may be missing out on these benefits.

The SKL presentation was co-authored by Nick Clague (SKL Europe) and Mike Brown (SKL America). A copy of the presentation may be requested by contacting Nick.Clague@sk.com or Mike.Brown@sk.com.