ENGINE OILS: Adding a Plus

Sept. 1, 2004
While often reflects marketing hype rather than any real extra capability, that is not the case for CI-4 PLUS. The latest engine oil classification enhancement from the American Petroleum Institute (API), CI-4 PLUS closes a small but very real gap between the expected conditions of 2002 low-emission engines and what's actually taking place in the real world. Originally, the '02 engines were scheduled

While “plus” often reflects marketing hype rather than any real extra capability, that is not the case for CI-4 PLUS. The latest engine oil classification enhancement from the American Petroleum Institute (API), CI-4 PLUS closes a small but very real gap between the expected conditions of 2002 low-emission engines and what's actually taking place in the real world.

“Originally, the '02 engines were scheduled to be introduced in ‘04, but the EPA consent decree moved the date up a full two years,” explains Gary Parsons, commercial automotive business unit manager for ChevronTexaco. As a result, both engine makers and lubricant developers had to alter their product development timelines dramatically, he adds. The CI-4 category was established in December 2001, a mere 10 months before the introduction of '02 low-emission engines.

According to Mark Betner, manager of heavy-duty products for Citgo Petroleum, that created a situation where ‘02 engines were being designed and developed parallel to the oil, rather than in sequence.

“CI-4 was the first oil we developed where we didn't have engines in the field to do the testing that we would have liked,” points out Dan Arcy, technical product marketing manager for Shell Lubricants. “We're usually given more time to field-test prototypes in the real world, to see how they performed, and then formulate the oil accordingly.”

Although CI-4 proved to be very good, says Arcy, lubricant makers and engine OEMs found that in some cases the soot being generated by cooled EGR was much higher than expected. In addition, it was almost a different kind of soot, one that thickened the oil much more rapidly. “So we needed to adjust the oil to handle what was happening out in the field,” he adds.


Mack discovered that its ASET internal-EGR engine, designed for vocational applications, needed more soot dispersion capability and better shear stability than that required by CI-4, so it introduced the Mack EO-N Premium Plus '03 spec.

“To meet the requirements of EGR engines, most lubricant formulators were moving towards higher ash oils with more base reserve, helping to improve oxidation resistance, improve acid neutralization capacity and improve soot dispersion performance,” explains Parsons.

However, Caterpillar, which uses ACERT (Advanced Combustion Emission Reduction Technology) rather than EGR to meet the stricter emissions requirements, grew concerned that higher ash oil formulations would lead to higher piston deposit levels, so they introduced the Cat ECF-1 spec to put a “cap” on the total base number (TBN) for CI-4 oils.

Companies making engines equipped with EGR then responded with oil specs designed to make sure the TBN didn't drop below a certain level, which might rob the oil of critical protective properties their engines needed.

“Cummins, for example, revised their CES 2008 specification to place a lower limit on the base reserve in the oil to assure proper acid neutralization capacity,” says Parsons. “Every six months, it seemed, we were getting new and different OEM oil specs.”

These different specs made the lubricant developers' job increasingly difficult, since meeting each spec required additional dollars to be spent on testing and certification — money desperately needed to fund development of the PC-10 oils needed for engine and aftertreatment systems designed to meet much stricter emission rules in 2007 and 2010.

The real issue with PC-10 oils is that they will not only be costly to develop, but costly to test as well. Parsons says the development costs for a new oil formulation average roughly $1-million and must pass 15 tests to meet the current CI-4 oil standard. For PC-10 oil, however, testing costs alone may rise to between $110,000 and $150,000 per test because of the new demands placed on oil for use in '07-compliant engines.

“We're looking at trying to reach ash levels of about 1% and having a TBN of about 8, compared to the 11 TBN standard we work with now,” Parson explains. “That's going to change things significantly.”


Rather than open the door to an endless proliferation of engine model- and brand-specific oil specs, engine makers and lubricant developers came together last year and asked API for an enhancement to its CI-4 category. CI-4 PLUS is the result.

“Let me stress that CI-4 PLUS isn't a new category; it doesn't mean that CI-4 is going away or is being changed,” says Kevin Ferrick, API's manager of engine oil programs. “It's an enhancement designed to meet a specific set of engine conditions.”

Creating an industry performance standard using API's classification system also forged a gentlemen's agreement of sorts among all the engine manufacturers. In essence, they agreed that the CI-4 PLUS spec would be the last formal addition to API's classification list until 2007, says Parsons. “That will allow us to focus on the final lap of developing oils for 2007 and beyond,” he adds.

Ferrick noted that the speed at which CI-4 PLUS came into being — just shy of 12 months, compared to a more typical two- to three-year timeframe — underscores how important all the industry participants considered this enhancement to be.

“We didn't have to go through the regular testing cycles because Mack gave us the data from its T-11 engine oil test to form the basis of CI-4 PLUS,” says Shell's Arcy. “That's why we were able to ‘bolt on' an enhancement or supplement to CI-4 so quickly; if we'd had to go through the regular process it would have taken much more time.”

It's extremely expensive to bolt on supplements to current industry oil specs, so the goal is still to get it right the first time. But “it allows us to move quickly to handle an unforeseen or unexpected occurrence,” Arcy points out. “We developed the fast-track process just in case we're faced with something similar in 2007. I think that's very unlikely, though, as we [expect] to have more field-testing opportunities with '07 technology.”


Another benefit to CI-4 PLUS oil is that it's designed to handle potentially longer drain intervals, according to Alex Bolkhovsky, commercial vehicle technical advisor for ExxonMobil.

“This oil is designed to offer more viscosity control, greater soot loading capability, and better shear stability,” he says. “Shear stability and soot handling are the real benefits to a fleet trying to go to extended drains post-'02, as well as giving them a little more peace of mind that the oil can handle the EGR environment.”

The key, says Chevron's Parsons, is that oils meeting the CI-4 PLUS spec will provide extended drain capabilities in ‘02-compliant engines as well as older models. This, combined with improved soot dispersion, means that the oil can stay in the engine for a longer period of time.

ExxonMobil's Bolkhovsky emphasizes that since CI-4 PLUS is fully backward-compatible with other specs and earlier generations of engines, “both older and newer engines will benefit from its use.”

CI-4 PLUS will particularly benefit those fleets that have soot or shearing issues in their older trucks, he says. “It's going to offer better wear control, particularly in guarding against wear at startup, which is where most engine wear occurs,” Bolkhovsky points out. “Older trucks will definitely see a benefit. And it could help extend drain intervals since CI-4 PLUS has greater soot handing capability.”

In terms of cost, deciding whether to stock two different oils or use only CI-4 PLUS oils will depend on a fleet's engine makeup and wear concerns.

“Most fleets prefer to stock only one oil; it makes greater sense from an inventory perspective,” says Bolkhovsky. “However, fleets that have well-controlled maintenance operations and [use] only a few of the engines CI-4 PLUS is designed for may decide to stock two different oils. It all depends on their operational needs.”

What's the difference?

How is CI-4 PLUS different from CI-4? Here are the highlights:

  • The CI-4 PLUS designation is located at the bottom of the donut, which is not where most fleets will expect to find it. “The top of the donut typically refers to the oil's performance category; the middle relates to its SAE viscosity grade, [and] the bottom is usually reserved for the passenger car market to denote energy conservation properties,” says Shell's Dan Arcy. “But it was too complex to try and fit CI-4 PLUS in the top part of the donut; we ran out of space. Having it in the bottom will make it easier to see.”

  • Test data used to set the CI-4 PLUS standard comes from a single OEM — Mack Trucks and its T-11 engine test — rather than a program developed and sponsored by the industry as a whole.

  • The key additional benchmarks for CI-4 PLUS are a thickening test, i.e., how much soot the oil can handle before turning into sludge; and a shear-stability test that now runs for 90 cycles, rather than the 30 cycles required by CI-4 standard.

Is it worth it?

As CI-4 PLUS oil officially becomes available on the market this month, it's most likely going to cost more than its CI-4 predecessor. But Reginald Dias, director of commercial products for ConocoPhillips Lubricants, says choosing a particular oil formulation solely on price isn't always the best way to go.

“The cost vs. benefits evaluation cannot be made strictly on the purchase price alone,” he notes in terms of selecting CI-4 PLUS vs. CI-4. “For an operator, the total lubrication cost includes the purchase price and the life-cycle cost: the cost of maintenance and downtime.”

Dias adds that getting more capability out of a particular grade of oil — in terms of longer oil drain intervals, for example — can more than offset the higher initial purchase price.

“CI-4 PLUS oil provides added protection and performance benefits not afforded by the previous generation oils,” he says. “Though the cost and benefits may not be specific or will vary depending on the equipment and type of service, [higher] pricing is often offset by the added value that comes with a higher performance product.

Decision time

Do your ‘02-compliant engines need CI-4 PLUS? That's a question many fleets may be asking themselves this month as the new category “enhancement” is rolled out.

Citgo Petroleum's Mark Betner wants to emphasize a critical point as the debate over whether a fleet does or does not need CI-4 PLUS oil heats up: Don't guess.

“This is not a broad-brush oil spec change; CI-4 PLUS is designed to deal with a certain set of conditions,” he explains. “The only way to truly know if you need this oil is to analyze the oil. The oil analysis process is the only way you'll get — with 100% certainty — the information you need to make that decision.”

Betner says CI-4 PLUS is only going to benefit a limited percentage of the market, which is why fleets need to decide for themselves whether or not they need it. “Have your lubricant supplier help you conduct an oil analysis,” he advises. “Don't make the decision… based on guesswork and hearsay.”

About the Author

Sean Kilcarr | Editor in Chief

Sean previously reported and commented on trends affecting the many different strata of the trucking industry. Also be sure to visit Sean's blog Trucks at Work where he offers analysis on a variety of different topics inside the trucking industry.

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