If recent announcements from truck manufacturers are any indication, the next generation of heavy-duty truck models and engines will be an evolutionary step forward in terms of greenhouse gas emissions and fuel efficiency.
The effort will target a number of truck and engine design elements, from aerodynamics to advanced engine technologies. Some OEMs have suggested that these new technologies will allow fleets and owner-operators to spec, purchase and operate a 10-mile-per-gallon truck by the beginning of 2016.
A key component in this fuel efficiency push will be a new category of engine oil. The new oil will feature lighter viscosity for enhanced fuel economy—but will likely be presented as a “split category” to insure continued protection for today’s engines.
The desire for a lighter weight engine oil is basic physics, says Dan Arcy, OEM Technical Manager for Shell Lubricants. Simply imagine rotating your arm in a bucket filled with water, and then making the same motion in a bucket filled with butter. Obviously, you will expend less energy moving your arm through the thinner fluid.
The same principle applies in next generation engines: Even though the parasitic energy loss created by forcing an engine to churn heavier oil is tiny compared to other factors such as aerodynamics or decreased tire rolling resistance, it is a significant enough efficiency gain—up to 3 percent compared to current 10W/30 viscosity oils in use today.
Oil companies and engine manufacturers have been working together with the American Petroleum Institute to define, create and test and validate the industry’s next-generation diesel motor. The new oil, which has been designated Petroleum Category 11 (PC-11) is scheduled to appear on the market in January, 2016—one year in advance of federally-mandated Greenhouse Gas emission compliant engines.
The new oils (and the engines they will run in) are so advanced that the petroleum industry is also being forced to establish a whole new slate of tests to qualify the oils, Arcy adds. “We also anticipate some of the current tests will need to be updated by the 2016 timeframe.”
Arcy says it is likely the new oil will appear in two distinctly different formulations – what the industry calls a “split category.”
“The new category is being divided into two viscosity grades,” he explains. “One will be heavier like today’s oils. The second will provide fuel economy benefits. The challenge will be creating a low viscosity oil.”
James McGeehan, global manager of diesel engine oil technology for Chevron Lubricants, says the new oil will be the first-ever split oil category. “This will assure backwards compatibility for pre-2017 diesel engines as well as optimal emissions and fuel economy for 2017 engines,” he says. “The new oil must also work for off-highway engine manufacturers such as Deere and Caterpillar.”
As a result, McGeehan says, the first new oil, likely to be designated API CK-4, will be blended to be fully compatible with older oil categories back to CH-4, thereby preserving lubricity performance for older vehicles while providing protection for new emissions and GHG technologies that will begin appearing on engines as 2017 draws near.
“On- and off-highway segments may have different requirements as well for the same engine. Until the spec is fully defined, engine and truck manufactures will not make their final recommendations,” Arcy says.
As of now, he says, a separate oil category will be blended specifically for 2017 and later engines with an emphasis on fuel economy and meeting Greenhouse Gas emission standards. It will be up to each engine manufacturer to specify which oil will be spec’d for their engines.
There will be some real-world benefits beyond fuel economy, though, according to McGeehan. “It will allow engine manufacturers to dramatically reduce, or even eliminate, in-cylinder EGR levels,” he says. “This will minimize soot in the exhaust stream, reducing the load on diesel particulate filters and the number of regenerations required. Some 2017 engines could be completely EGR-free, resulting in air management enhancements, reduced radiator sizes, reduced parasitic power loss and internal friction as well as extended drain intervals while running efficiently at lower rpms.”