Even as 2003 runs out, much remains up in the air about how the 2007 diesel engine emissions regs will play out-especially whether or not trucking will have to say “so long” to the backward compatibility of motor oil that heavy-duty fleet operators have long enjoyed.
“Backward compatibility” may not be an elegant term be but there's no better way to say a new oil-service category has been formulated to protect not only the latest engines available but all previous “legacy” engines as well.
It's a practical concept that is endorsed by engineers, who tend to favor getting jobs done as simply as possible, and by fleet mangers, who certainly prefer keeping one oil on hand rather than two.
Never advertised and always taken for granted by consumers and truckers alike, backward compatibility has been a feature of diesel and gasoline motor oils ever since the American Petroleum Institute (API) started decades ago putting donuts on oil cans to denote which service category a lubricant meets.
The next API oil-service category, now under development as Proposed Category 10 (PC-10), will be formulated to protect the ultra-low-emissions heavy-duty engines EPA will require to be sold starting in '07.
Those engines will likely use EGR, will have to run on low-sulfur fuel and will require aggressive aftertreatment systems (see FO 7/03, pg. 16).
Although it's too early to know the specifics, in general PC-10 motor oils will need properties that will protect the new engines from wear while not harming their aftertreatment systems. But ensuring those twin objectives are met may leave the oil unable to fully protect pre-'07 engines
This chemical conundrum may mark the end of the road for the backward compatibility of diesel engine oils.
The other possibility is that PC-10 oils will indeed be backward-compatible — but only if oil drain intervals are shortened for pre-'07 engines. Conceivably, that could result in oil marketers formulating product specifically designed for extending drain intervals of pre-'07 diesels only.
While API does the actual licensing of each oil-service category, it's the ASTM (American Society of Testing & Materials) Heavy-Duty Engine Oil Classification Panel that sets the limits and verifies the testing used to develop each category.
The panel's members are representatives of major oil and additive suppliers, as well as engine makers. The chairman is Jim McGeehan, manager of global heavy-duty engine oil technology for ChevronTexaco Global Lubricants (CTGL), who has served on the panel since category CE was cooked up.
BACKWARD IN MIND
According to McGeehan, backward compatibility is indeed one of the goals being set for PC-10 oils. He expects the actual category resulting from PC-10 will be in place by mid-'05, giving oil formulators ample time to make product commercially available by the third quarter of ‘06 to dovetail with the mandated arrival of low-sulfur diesel fuel, which will be required for '07 engines and their aftertreatment systems to function.
There is a further complication. Low-sulfur fuel will be “phased in” between 2006 and 2010. The EPA has said that 80% of the fuel sold in the U.S. after June ‘06 must be 15-ppm diesel, with the remaining 20% allowed to be 500-ppm diesel. After 2010, 100% of the diesel sold in the U.S. must have the lower 15-ppm sulfur content.
Also clouding the oil outlook, if not the engine picture itself, is the undetermined “technology path” individual engine makers may follow to meet the '07 and then the 2010 emission regs.
Adoption of an exhaust aftertreatment technology known as selective catalytic reduction (SCR) tosses in one monkey wrench. SCR injects urea (ammonia) into the exhaust stream.
Some engine makers have already elected to use SCR to meet the next big European emissions cut, slated for 2005, to benefit from the economies of scale that using one technology in two major markets would afford.
However, the U.S. Environmental Protection Agency (EPA) has repeatedly expressed doubts about SCR since its wide use would require a new infrastructure to distribute urea. And if urea holding tanks are not refilled due to lack of material or to “cheat” the emissions equipment, engine emissions will climb sharply.
ChevronTexaco's McGeehan speaks of the “chemical box” that the ASTM panel members, and by extension the oil and additive industry, are awaiting to learn about. The box, essentially, represents the chemical limits engine makers will require PC-10 oil to reach.
“One thing that is coming out about '07,” says McGeehan, “is this reduction in emissions will be so significant that EPA itself regards it as an historic event.
“To be clear, the new limits will be strict enough that each engine maker will have to use some sort of exhaust aftertreatment system,” he says.
“To meet the emission limits for particulates, predominantly composed of soot and sulfate deposits, it appears that each engine maker will use a particulate trap coupled with an oxidation catalyst for unburned fuel,” says McGeehan. It's the nitrous oxide side of the equation that makes '07 so interesting. “To meet the NOx limits,” he explains, “some engine makers will continue to use EGR but they may also use aftertreatment systems, chiefly a NOx adsorber and a lean catalyst or selective catalytic reduction (SCR) which requires urea.”
McGeehan says ChevronTexaco “sees the need for lubricants that will be compatible with the various aftertreatment systems that may be used
“All the engine manufacturers are keeping their cards close to their vest,” he adds. “We may not know their final decisions before the end of this year.”
And the wild card in all this is SCR. “Volvo's Volvo and Mack units and DaimlerChrysler and its Detroit Diesel operation are all arguing for SCR as their preferred approach to cutting NOx,” explains McGeehan.
These companies favor SCR largely because they've already headed down that technological path to meet European diesel emissions regs and because it may provide better fuel economy than other NOx aftertreatment systems.
The sticking point with SCR is the urea holding tanks that will have to be mounted — and kept charged and operational — on trucks for SCR to work.
While EPA has stated repeatedly that it is “neutral” on the technology that engine makers will choose to deploy to meet '07 regs, it has also made it pretty plain that it must be convinced that a urea infrastructure can be put in place and that there will be some way of ensuring fleets and operators can't accidentally or otherwise allow the trucks to operate without the urea doing its job.
“We are committed to the smooth implementation of these regulations,” says EPA's Christopher Grundler, deputy director of the Office of Transportation & Air Quality.
“Our concern with SCR and urea,” he states, “is with the [existence of] infrastructure and compliance with EPA standards.
“The question is what happens when the onboard urea tank is empty,” he continues. “The driver will see no change in performance but the truck will be spewing out pollutants. It is not our burden to solve this but [engine makers] would have to have a solution to be certified.”
At press time, it remains to be seen if any engine maker will use SCR. Volvo Trucks North America has revealed it is running a test of SCR-equipped engines with a U.S.-based fleet. But according to a spokesperson, even if Volvo elects to use SCR here, it may not employ the exact setup under test.
Bringing oil back to the fore, McGeehan says that “regardless which way the engine makers go on aftertreatment, PC-10 will ensure there is one engine oil to protect all '07 engines.”
As McGeehan sees it, major fleet customers will push for one '07 oil to avoid misapplication issues. “We definitely have many fleets with mixes of engine makes here in the U.S. so having one oil is essential.
“And I honesty believe we can protect '07 engines with one oil-service category. Because the particulate trap aftertreatment technology will be a common feature across engine lines.”
As for ASTM, McGeehan says the goal of the oil classification panel is to have PC-10 oils in the marketplace by the third quarter of ‘06, or well before '07 engines are delivered.
To get there, McGeehan reports, the ASTM panel has queried engine makers on what chemical requirements will have to be met by PC-10 oil for it to be compatible with '07 aftertreatment systems.
“We have asked for replies by the end of this year but I think we should give them until the middle of next year to provide solid data. We're asking them to define what can be termed the ‘chemical box’ to ensure the oil will both provide engine durability and not harm the aftertreatment system.
“As for backward compatibility,” he continues, “that will be determined by the limits — the chemical box — the engine makers propose. If they want significant reductions in sulfated ash, phosphorus and sulfur, then PC-10 may not be backward compatible.”
According to Alex Bolkhovsky, product advisor-commercial vehicle lubricants for ExxonMobil, “there's no easy road to PC-10, as the aftertreatment systems under discussion have different appetites.”
He agrees that the process can go forward once engine makers determine the chemical limits for formulating the oil.
“The big challenge,” says Bolkhovsky, “is whether there will be a single oil that meets all aftertreatment requirements and is backward-compatible to protect pre-'07 engines.”
NO HARD DEADLINE
He says right now oil formulators can engage in “preliminary investigations to identify chemistries that could be applied but there is no hard deadline as to when we will get the information that would comprise the chemical box.
“The good news,” he adds, “is the industry is working very closely together, lube and additive suppliers along with engine makers.”
While he's confident work on PC-10 will forge ahead, Bolkhovsky points out that some engine makers are also asking for an “upgrade” of the current API CI-4 (for ‘02 and earlier engines) “to ensure they have a very robust category for older engines.”
Bolkhovsky says some engine makers would like the category revised to ensure improved soot control and shear stability and that Caterpillar would like it to be “truly tested” for its ACERT engines.
“But trying to put this upgrade in while working on PC-10 could cause slippage,” Bolkhovsky contends. “An upgraded spec for CI-4 will be released eventually — exactly when is the question.”
As to the larger issue of backward compatibility for PC-10, Bolkhovsky says “until we have the final word on chemical limits from the engine makers, we won't know if we will be able to deliver backward compatibility. We will know a lot more a year from now.”
He is quick to add that “either way, no one will be left out. It' s just a question of whether there will be a one or two oil solution to cover all engines.”
“When it comes to oil,” Mark Betner, heavy-duty lubricants manager for Citgo Petroleum Corp., says wryly, “we are all spec'd to death right now. “Despite all that went into the creation of CI-4 for ‘02 engines it was impossible to predict all the consequences of the hardware choices made by engine makers. The result has been various ‘performance plus’ specs released by the engine companies.
“What we hope is that by the time we get to ‘06,” he continues, “we will not have to reformulate oil for existing engines.
According to Betner, the big thing to bear in mind about PC-10 is that particulate filters, NOx adsorbers and SCR systems “are all chemically incompatible with today's CI-4 oils.
“That,” Betner says, “is what gets us to the likelihood that PC-10 oil may not be backward-compatible for approved use in pre-'07 engines. But working together, oil engineers and additive suppliers may be able to find a way.”
Given the need to meet that challenge, Betner sees “no need to reinvent” CI-4 by requiring a new API category for current engines. “What we need to do,” he affirms, is move onto developing PC-10.
“Whatever we do,” Betner adds, “our goal will be to protect engines. It's too early to tell but the solution may hinge on a number of factors, including how long drain intervals are expected to be or even how long aftertreatment systems are expect to last-and that may not be as long as the engines themselves.”
“We have ideas about whether there will be one or two oils by '07,” says Dan Arcy, product marketing manager for Shell Lubricants (which includes the Shell, Pennzoil and Quaker State brands). “But no engine maker has come out with a commitment to the hardware they will use for '07.”
For his part, Arcy cautions against viewing backward compatibility as the holy grail of oil. “Engine makers are saying they want PC-10 to be backward-compatible but they will still accept it if it is not,” he maintains.
“But to do the most efficient job,” he continues, “it seems we may need two different oils. It's way too early to tell about PC-10 but that oil could be significantly different than today's CI-4.”
According to Arcy, the heavy-duty oil classification system has worked quite well. “But after CI-4 was determined, some engine makers' conditions changed enough that they would like to see a new category designed to protect current (post '02) production engines.
Arcy says Shell prefers to have the development pf PC-10 remain focused on meeting the needs of '07 engines so that oil can be formulated by January '06.
“We don't want to end up behind the eight ball or lose focus by working on another API category [for existing engines] at this time,” he states.
Rather, Shell believes the OEM specs that would comprise a ‘CI-4 Plus’ oil are on hand and “we would support a new API category covering such requirements-but only if it does not impede progress toward completing PC-10.”
As for the backward compatibility of PC-10, Arcy says simply “we can deal with that issue if and when it arrives. The potential exists for the industry to end up with two different oils, one for pre- and one for '07 engines. And it does not hurt to make fleet managers aware of this possibility now.
“A year from now,” he points out, “we will have determined the requirements of PC-10 oil. Then we can start testing so that a year later we will know whether backward compatibility will be an issue.
“And, Arcy adds, “there is the possibility that backward compatibility may be retained — but with shorter drain intervals for one set of engines.”
Backward compatibility or not, one thing is certain. Oil formulators are determined engines will be protected by their products. The devil, though, remains in the yet-to-be revealed details. And only the engine makers can spell those out.