SLIPPERY SITUATION
Oil developers say meeting the 2007 standards will be tougher than ever.
Deborah Lockridge
Senior Editor
The next round of emissions standards could mean some changes in your engine lube maintenance — perhaps some expensive ones.
Come 2007, you could be paying more for engine oil and oil filters. For one thing, there could be more filters on the engine to buy and replace. You might even have to carry two types of oil, especially if you want to keep extending drain intervals in your older engines.
The details of how each engine manufacturer will meet the new particulate and nitrous oxide standards aren't yet known, but from what we know so far, it looks like the new engines will pose a significant challenge for engine oils. In fact, oil developers say the 2007 regulations are a bigger challenge than any of the previous EPA standards.
What is known is this: Engine makers will no longer be able to meet these standards solely with changes in the combustion chamber. Various "aftertreatment" devices will have to be used to treat the engine exhaust itself. And that's a new challenge for the engine lubricant.
"With past oil categories, we've been primarily concerned with what's happening in the engine itself," explains Tom Weyenberg, a heavy duty diesel manager at Lubrizol, which makes the additives that affect an oil's performance. "For instance, keeping the pistons clean of deposits, keeping the oil flowing well under conditions of high soot.
"Now, for the first time, we have to add a whole area of performance to the lubricant — and that's protecting these aftertreatment devices," he says.
Chemistry Lessons
Aftertreatment devices will definitely be used to address the biggest change in the EPA regulations — a huge reduction in the amount of particulate matter allowed in the exhaust. "We're looking at a 90% reduction in particulate matter," says Alex Bolkhovsky, commercial vehicle lubricant technical adviser for ExxonMobil. "It's been almost a decade since EPA targets have hit on particulate matter."
All the major engine manufacturers intend to use particulate traps to meet the limit for particulate matter. These are special filters that catch particulates and at intervals burn them off.
The problem particulate traps pose for the oil is that engine lubes' additives result in ash in the combustion process. A tiny bit of the oil gets burned up in the combustion chamber, and that burned — or sulfated — ash can clog a particulate filter. So oil makers will need to use new kinds of detergents that don't result in ash.
Detergents allow the oil to handle more soot. While most of the 2002 engines did not put as much soot into the oil as initially expected (it varies by manufacturer), some people are predicting that the new oils will have to handle even more soot. So some other method of holding soot in suspension must be developed.
Ash also results in a higher total base number, or TBN and if ash is reduced, so also will TBN.
The other aspect of the 2007 regulations is another ratchet up on the limits for nitrous oxide, or NOx. Most engine makers apparently will use versions of their 2002 engine technology to hit this target. Caterpillar has said it will use its new ACERT technology for 2007. Volvo, Mack and Cummins have announced they will use exhaust gas recirculation technology, already used to some extent on their 2002 engines. EGR reduces emissions by returning a portion of exhaust gases back into the engine's combustion cycle. The recirculated exhaust lowers the combustion temperature, which inhibits formation of NOx. Most engine manufacturers are expected to opt for higher levels of EGR for NOx control.
One option that has been considered, and in most cases rejected, for 2007 engines is selective catalytic reduction. SCR is an engine aftertreatment technology where an ammonia-based urea fluid is injected into the exhaust. This method is believed to result in better fuel mileage than other options and is already used in Europe. However, it would mean another fluid system on the truck, and it will require an infrastructure where trucks can fill up with urea. While at this point it doesn't look as though it will show up in 2007 engines (Freightliner's Detroit Diesel is said to be considering it but at press time had not yet made an announcement), SCR could be a factor in the next round of emissions reductions in 2010. (NOx adsorbers, which convert NOx into harmless nitrogen, are another technology that may be ready by 2010.)
Even without SCR, engine manufacturers may have to use some other sort of aftertreatment to reduce NOx, most likely involving a catalyst, similar to catalytic converters on automobiles. The challenge for oils is that the catalyst can be made ineffective by compounds other than NOx. Of most concern are sulfur and phosphorus in the oil. Phosphorus is one of the biggest anti-wear additives used in engine oils today, so oil makers need to look for ways to prolong engine life without phosphorus. Sulfur, which also can affect EGR systems, is a common component of many additives in the lubricant, and part of the base stock as well.
One factor that will help lubricant formulators is the introduction of low-sulfur fuel in 2006, notes Mike Lynskey, marketing and technology manager for Castrol Heavy Duty Lubricants. This will reduce the amount of acids that the lubricant needs to neutralize. Lynskey says the drive to reduce sulfated ash, phosphorus and sulfur has led the industry to coin the term "low SAPS formulations" as we move toward 2007.
In short, "The oil companies have a real complicated chemistry lesson to be worked out," says John Clevenger, director of global product management for Fleetguard.
Defining A New Oil
All these issues will be addressed in the next heavy duty diesel engine oil standard set by the American Society for Testing and Materials (ASTM). The name of the proposed category, which eventually will replace the current API CI-4, is PC-10. (The final name is not yet known; it could be CJ-4 or, more likely, CK-4.)
The oil classification panel has asked the engine manufacturers for input on what the chemical limits should be on the new engine oils to ensure particulate filter life. Those limits are expected to be known by the middle of this year, so the committee can move along in the standards process.
Defining this "chemical box" is a new tactic for the committee, says chairman Jim McGeehan, who is also global manager of diesel engine oil technology at ChevronTexaco. This was necessary, he says, because there is no field testing showing the effects of current engine oils on the new technology the engine makers will likely be using.
Meanwhile, the committee is developing engine tests that oils must pass to earn the new category designation. Even though there's a new focus on aftertreatment, says Lubrizol's Weyenberg, part of developing the new oil category still includes defining basic engine performance for areas such as wear, deposits and oxidation. The timeline calls for defining the category limits by the middle of 2005, with licensed products available by mid-2006.
The plan is for this new oil to be "backwards compatible," meaning it can be used in older diesel engines as well as the new 2007 models. Without this backwards compatibility, trucking companies, dealers and truckstops would have to stock two different kinds of oil, and that leads to the potential to get the wrong oil in the wrong engine. Oil manufacturers disagree on the feasibility of backwards compatibility with the new oils.
The key factor, says McGeehan, is the sulfated ash limit. "Hopefully the manufacturers will define that chemical box in the order of 1% sulfated ash," he says. (Current sulfated ash levels in CI-4 oils average about 1.3% and can range as high as 1.6%.) "If it is, we should be able to deliver products that are backwards compatible. But if they come up with some very low ash levels — which I don't think they will — we could have a separate oil for these engines."
The subject of backward compatibility "is a pretty hot topic," Weyenberg says. For years, he says, fleets have enjoyed the benefits of mixed-fleet oils that can be used in everything from 18-wheelers to dump trucks to the boss' pickup truck.
ExxonMobil's Bolkhovsky notes that there is still a concern, not that the new oils won't properly lubricate older engines, but that their drain intervals might not meet customer needs. "There is still the potential that customers who want to maximize drain potential in older engines could carry two lubricants," he says.
According to Weyenberg, "We might be approaching a time where we don't have a single oil to lubricate all pieces of equipment. The oil may technically be backward compatible, but maybe the economies are against it, from the drain intervals that result as well as the cost of the oil. So these are some of the tradeoffs that are going to be facing fleet maintenance managers come 2007."
Expensive Challenge
Oil makers agree that this is the biggest challenge they've faced in developing new lubes for low-emissions engines.
"Since 1988, when we developed CE, we have had incremental improvements all the way along," McGeehan says. "This is the first time where we're going to apply a chemical box that really could make some major changes, where we have to cut down on the level of detergent and come in with some new wear inhibitors. So this one is a bigger challenge — and we have a shorter time frame in which to do it. We won't know how big a challenge until we get the results of this chemical box later this year."
Additive makers such as Lubrizol aren't wild about the idea of chemical limits. "If we were painters, it would be like taking colors away from our palette," says Weyenberg. "It constrains the way we formulate lubricants. To make up for lower levels of phosphorus, for instance, we have to use higher rates of other compounds, and typically more expensive compounds."
Which means the price of oil may well go up.
"Every time we look at a new oil category, the issue [of price] comes up," says Dave Taber, technical coordinator for heavy duty engine oils at ConocoPhillips, "but in reality, when the new oils hit the market, there has not been a lot of change in cost. But this time it might be different, because there's going to be a lot of new technology that comes into play. We're looking at probably some pretty radical changes for these new oils."
Filters
Meanwhile, filter manufacturers are playing a guessing game and trying to research new technologies they might need to meet the needs of the new engines.
"You've got to look at the whole system," says Fleetguard's Clevenger. "The oil and filter work together. The oil holds contaminant in suspension, and the filter takes out the contaminant that's in suspension. It's a very symbiotic relationship. "
Changes in oil chemistry may call for filters to have changes in gasket materials, plastics, adhesives, and the filter media itself. With the possibility of more soot being suspended in the oil, filtration efficiency and capacity may need to be improved, possibly with the use of more filters on the engine, especially bypass filters.
Chris Greeson, senior technical manager at Wix Filters, says "it's anybody's guess" at this point how many filters will be on the engines, what kind of oil blends will be used, what kind of pressures and temperatures filters will have to endure, and how much of a problem sludge will be. "There's a ton of R&D going on, and we are trying to prepare ourselves for as many case scenarios as we can imagine — and hopefully we guess right."
One thing filter makers are predicting is greater use of bypass filters. "Because it's a slow flow area, you can use all types of media to do a whole lot better job of cleaning the oil of contamination, moisture and sludge," Greeson says.
Some people are predicting that the 2007 oils will put more soot into the oil. Removing that soot is an area where bypass filters excel, according to Fleetguard's Clevenger, especially the centrifugal type. In addition, he says, soot tends to agglomerate, or stick to, the organic contaminants in oil that form sludge. Sludge tends to plug filters, but bypass filters using depth media can be very good at organic contaminant removal, he says.
Bypass filters also mean more total filter capacity, which is an issue with extended drain intervals, Greeson says. With the 2002 engines, most people backed off on massively long drain intervals because of the extra demands put on the engine oil. "The bypass filter adds dirt-holding capacity to the oil filtration system, and when you do that, you have a better chance of going back to something called extended oil drains," Greeson says. "I don't think there's any hope we'll be back to 50,000 miles or more without the truck leaning to one side because there's 38 filters on it."
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