June 1, 2002
That awkward engineering phrase backward compatibility is taking on another and welcome meaning as the age of EGR diesels dawns. So far, when it comes to motor oil, backward compatibility has meant that a product complying with the latest API (American Petroleum Institute) service category, such as CH-4, developed specifically to benefit the newest engines on the market would just as fully if not

That awkward engineering phrase “backward compatibility” is taking on another — and welcome — meaning as the age of EGR diesels dawns.

So far, when it comes to motor oil, backward compatibility has meant that a product complying with the latest API (American Petroleum Institute) service category, such as CH-4, developed specifically to benefit the newest engines on the market would just as fully — if not more so — protect all previous engines. Those earlier powerplants, of course, had up until that point been protected by a lube meeting whatever the previous API category was, in this case CG-4.

This approach has worked nice and neat for decades, ensuring that new engine technology had the proper lubrication available when it came on the market and that fleets never had to stock two different API oils.

The certification system has even held up in the face of the Environmental Protection Agency (EPA) cranking out regulation after regulation to make diesel engines less polluting. The succession of cleaner engines rolled out in the '90s required ever harder-working oil and the engineers directing the API certification process kept pace, developing the CG-4, then CH-4 and now the CI-4 oil-service category.

CI-4, a category that oil companies will officially be able to market products with starting in September, arrives just in time for the first EGR diesels, which will hit the market the following month. Not only will CI-4 oil protect those newfangled powerplants, it will be fully backward-compatible for engines that have been using oil meeting CH-4 or other earlier API categories.

And that's just the tip of the dipstick. The really good news is that CI-4 oil will help fleets apply their existing drain intervals to new EGR engines and — drum roll, please — may enable them to further extend the drain intervals of their existing non-EGR engines to boot.

Bear in mind that the successful crossing of this bridge doesn't mean the industry doesn't have an even wider gulf to cross when it comes to protecting the next generation of engines to come — those that will have to meet the even stricter '07 emission standards (see box).

But for now at least, there is cause to pause and celebrate the chemical engineering triumph represented by CI-4 oil.

“There are three key demands on motor oil caused by the addition of cooled EGR, which makes engines run hotter, that the CI-4 category addresses,” explains Gary Parsons, global consumer and transport segment director for ChevronTexaco Global Lubricants. “These are greater soot-loading, acid neutralization and oxidation stability.

“The intent from the beginning,” he continues, “was to make CI-4 backward-compatible to all previous API diesel categories. And on top of that, we expected to get improved performance in engines that had been using CH-4 or CG-4 oils in most cases.”

As for extending drains on the EGR engines coming in October, Parsons contends that the goal of engine builders is “to keep drains similar” to today's levels.

Parsons suggests fleets that wind up pioneering with EGR engines come October proceed cautiously by conducting used-oil analysis to see how the new powerplants actually perform. “They might start sampling the oil after 10,000 miles,” he recommends. “Then they may want to fine-tune the drains by pushing the interval out by 5,000-mile increments as they gain actual experience in the field.”

According to Parsons, another key aspect of the extended-drain debate is the so-called “plus” specs that Cummins and Mack are issuing for EGR engines that are even stricter than the CI-4 category to help ensure extended-drain capability.

These are officially known as the Cummins CES20078 and Mack EO-N Premium Plus specs. And as happened with the previous category, it is likely that CI-4 oils that meet these extra specs will come to be referred to in industry shorthand (if not marketing parlance) as “CI-4 Plus” oils.

Whatever the verbiage, it is crucial to bear in mind that while all CI-4 oils will be appropriate for use in EGR and non-EGR engines alike, only those with the CES20078 and EO-N Premium Plus tags will be approved for use when extending the drains of those companies' EGR engines beyond their recommended standard intervals.

Got it? If nothing else, understanding the finer points of this issue suggests the demands on heavy-duty oil marketers to properly explain products to users may be just as tough as those placed on lubrication engineers toiling behind the scenes to reformulate oil.

According to Michael Ragomo, commercial vehicle lubricants product advisor for ExxonMobil Lubricants & Petroleum Specialties Co., the criteria set for certifying an oil to the CI-4 category results in products that “offer greater wear protection, more thermal stability, improved oxidation control and increased soot-handling characteristics. “CI-4 capable engine oils,” he continues, “are also fully compatible with virtually any diesel engine on the street today. I don't expect any major distributor in the U.S. or Canada to be selling current API CH-4 category oil by next fall.”

Ragomo says a fleet that will be operating both EGR and non-EGR engines may opt to stick with a single drain for all powerplants as long as they identify the “least common denominator” interval in order to protect the whole fleet.

“Unfortunately,” he notes, “many fleets would find it unmanageable to schedule multiple intervals for different engines. But fleets that wish to be more engaged in extracting the most value possible could set up different drain intervals for each engine type.”

In any case, according to Ragomo, fleets should look to their oil marketer for specific advice. “The oil supplier should help evaluate the severity of a given fleet's operation,” he explains. “Things that should be considered include fuel and oil consumption rates, loads hauled, duty cycles, and idling time.”

Allan Perry, product specialist for Tosco/Phillips' 76 Lubricants Div. explains that “because the CI-4 category was designed for protecting EGR engines, a more robust additive package was needed. Compared to the previous CH-4 category, CI-4 requires improved dispersancy for greater soot control, much better oxidation stability to protect against thermal degradation and improved protection against bearing corrosion.

“And each of these CI-4 features has a positive impact on extended-drain capability,” he continues. “However, there's no way to predict what percentage of improvement may be obtained. We would still recommend oil analysis as the safest and surest way to extend drain intervals, no matter the engine.

“At some point,” Perry predicts, “engine OEMs will publish their maximum recommended drain intervals for EGR engines. Keep in mind the goal of CI-4 itself was to provide quality oil that could at least maintain existing drain intervals when fleets moved to EGR engines.”

“We know CI-4 oils are much more robust chemically,” says Mark Betner, Citgo heavy-duty products manager. “If you track the biggest limiting factor on oil performance — soot-loading — you can see there has been continuous improvement since 1990.”

Nonetheless, Betner cautions fleets not to expect miracles. While CI-4 has changed oil, he says fleet operating conditions, engine type and maintenance practices have not. “The reason there is so much variation in opinions on what CI-4 can do,” he remarks, “is simply because there is very little field experience with EGR engines yet.”

As for general recommendations, Betner goes so far as to suggest that over-the-road fleets extending drains past 35,000 miles may want to revisit that figure if they start running EGR engines.

“People understandably want black-and-white answers,” he remarks, “but the reality is fleets must work with their own oil suppliers and perform at least benchmark oil analysis of a select group of powerplants.

“And we're not expecting a horror story when it comes to EGR oil drains,” Betner adds. “You just have to consider the specifics conditions present in each trucking operation to set the correct guidelines.”

On the other hand, Betner feels strongly that CI-4 will allow extending drains of non-EGR engines. “If, again, the proper approach is taken,” he says, “we can see those drains extending out to 50,000 miles.”

Ralph Cherrillo, technology advisor for automotive products at Shell Oil Products U.S., says “a lot more was built into CI-4 oils to deal with EGR so a mixed fleet of older and EGR engines will get a better product overall and the ability to extend drains on their non-EGR engines. But, with engine builders still being cagey about EGR's impact on oil performance, fleets may want to consider running different drain schedules.”

Greg Raley, Shell Oil product manager, concurs that OEMs are taking a conservative approach to EGR drain “With CH-4, many products met the Cummins and Mack extended-drain specs,” Raley points out “But it is a lot harder to meet Mack's EO-N Premium Plus and Cummins' CES- 20078.”

Raley says Shell recommends anyone using EGR engines go immediately to CI-4 oil. “Then if they want to extend drains on those engines,” he states, “they should rely on a good oil analysis program that produces trending results, not just a ‘snapshot’ view of where things are at one point in time.”

Brian Jacoby, district manager-field engineering for Castrol Heavy-Duty Lubricants, points out that when it comes to EGR, “no one is guaranteeing extended drains” at this point.

However, according to Jacoby, oil that exceeds CI-4 would offer a positive benefit to existing engines. “If it's good for EGR than it will be even better for existing engines,” he says.

“The smart thing may be to institute two drain intervals,” Jacoby continues. “For most trucking operations, EGR engines will constitute only a small population of their fleet for some time. This may be the best way to protect them without losing the advantage of longer drains for their older engines.”

Jacoby points out the good-news/bad-news aspect of all this engine talk. “Strictly EGR engines will be on the market only from '02-'06,” he remarks. “Then the next generation of emissions-compliant engines will arrive. And those will be an entirely different animal.”

Check the oil…

Information on CI-4 is available from these and other lube suppliers:

BP Lubricants 350

Castrol 351

Chevron 352

Citgo 353

Conoco 354

D-A Lubricant 355

Exxon 356

Kendall 357

Mobil 358

Pennzoil-Quaker State 359

Phillips 66 360

76 Lubricants 361

Shell 362

Sunoco 363

Texaco 364

Valvoline 365

New recipe

The next API oil-service “donut” — currently known as Proposed Category 10 (PC-10) — to get cooked up will protect the ultra-low-emissions engines EPA will require to be sold starting in 2007.

These engines will likely use EGR, run on low-sulfur fuel and require aggressive aftertreatment systems (see FO 4/02, pg. 48). Although it's far too early to know for sure, that combination of technology may very well sound the death knell for the backward compatibility of oil that trucking has enjoyed for decades.

A plain-English albeit Rube Goldbergesque explanation of what oil formulators are facing comes courtesy of Shell engineer Ralph Cherrillo: “Compared to CI-4, PC-10 will have to take the zinc anti-wear components out of the oil to remove sulfur and phosphorous that would poison the aftertreatment system that will be used to help clean the exhaust.”

And he says with those elements removed from the oil, it is “anyone's guess” whether that oil will fully protect earlier, that is pre-'07, engines.

That would mean no more backward compatibility, leaving fleets no choice but to stock and use two entirely different oils to protect their engines — a state of affairs that has never existed before.

But, says Cherrillo, there is “still hope of a technological breakthrough” that would enable formulating a PC-10 oil that would also protect older engines.

Time — and chemical engineering — will tell.

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