A tale of two oils

Nov. 8, 2012
The future probably holds two new engine oils

In just a few years’ time, the heavy-duty engine oil arena is very likely to get more complicated for fleet owners—albeit for very good reasons. The release of a new American Petroleum Institute (API) service category for heavy-duty motor oil (such as the current CJ-4) always starts with a discussion by engine makers and lube formulators of a “Proposed Category” (PC).

That’s not unusual. But this time around, the Proposed Category under discussion—PC-11—may well lead to the release of not one but two new API oil-service categories. To fully grasp what’s now driving heavy-duty engine oil development and thus PC-11, first look at the next wave of federal environmental rules for trucks. In a few years, truck OEMs in concert with engine makers will have to meet greenhouse gas (GHG) reductions and corresponding miles per gallon (mpg) increases for commercial vehicles that will go into effect in stages from 2014 to 2018.

Truck and engine builders are expecting motor oil to help them hit those targets. That’s why they have petitioned API for new oil-service categories. If created out of PC-11, the new categories would supplant the current CJ-4 category and become available for licensing via API by oil formulators on Jan 1, 2016.

The entity charged with recommending whether to proceed with a new oil category is called the New Category Evaluation Team (NCET). It’s comprised of representatives from the Truck and Engine Manufacturers Assn. (EMA), API, and the American Chemistry Council (ACC) as well as members drawn from oil additive suppliers and industry testing labs.

NCET must consider “all information being presented by engine makers to see how developing and releasing a new API category would affect the marketplace, other existing API categories and the environment,” advises Dan Arcy, global OEM technical manager for Shell Global Solutions and NCET chair. “The team must also consider the timing of the request, whether or not there are tests available [to prove it out] and if there is sufficient data to support changes in engine design.”

NCET’s recommendation will either be a “Yes” or a “No” by consensus. According to Arcy, a decision on whether or not PC-11 will be split into two proposed categories will likely not be formally made until sometime next year.

If NCET does recommend proceeding, creation of the new category is taken up by the Heavy-Duty Oil Classification Panel of the American Society of Testing & Materials (ASTM). This panel is charged with setting limits and verifying testing for the development of API oil classifications. The technical specs are ultimately relayed to API for licensing.

“PC-11 was launched to address the reduction in carbon dioxide [CO2] emissions from truck engines [due to the GHG/MPG rules] and to help engines be more fuel-efficient,” says Arcy. “The PC-11 challenge will be to develop specs for engine lubes to meet the need to cut CO2 and provide a fuel-economy benefit while not compromising engine life and durability.”

And that is such a tall order that EMA “recommended that PC-11 be split into two subcategories because of the desire to improve fuel efficiency while ensuring corresponding [protection] performance levels,” Arcy relates.

If they come to fruition, each of these new categories would help engines meet the lower CO2 standards of the GHG/MPG rules. Now the kicker: The difference between the categories would center on their impact on fuel efficiency.

Under the dual-oil scenario, the first new category would be formulated to “preserve the historical heavy-duty oil criteria [as represented by the current CJ-4 category] and be backward-compatible with existing on- and off-highway engines,” explains Arcy. While the second new category would also maintain engine durability, it would, in addition, deploy a lower-viscosity formula to significantly boost fuel efficiency compared to current CJ-4 15W-40 oils.


What’s more, according to Arcy, that second, fuel-efficient oil would provide only “limited backward-compatibility,” the actual scope of which would depend on OEM and engine maker requirements and vehicle applications.

There are other drivers pushing the development of PC-11. “NCET wants to address changes in the hardware of engines manufactured since 2006 as well as deal with the obsolescence of many of the engine tests used to develop an oil-service category,” says Arcy. “It’s worth noting that by the time work is done on this new category or categories, 10 years will have elapsed since the last category [CJ-4] came out.”

The lubrication engineer who’s chaired the ASTM Heavy-Duty Oil Classification Panel for the last 25 years—during which time seven new oil-service categories have been introduced— is Jim McGeehan, global manager of diesel engine oil technology for Chevron Lubricants. He affirms that the stated goal of EMA to have two new categories in place for licensing in 2016 is “still the position today, and there is no indication they will change it.

“Having [just] one oil that does it all is not feasible based on how the OEMs will specify their approvals,” McGeehan asserts. “For the off-road vehicle segment of customers, those OEMs have indicated today they want an oil that is backward-compatible with a normal oil film thickness for the upcoming new category; they are more interested in durability of their engines than fuel economy.

“On-road vehicle OEMs are interested in trying to achieve the best fuel economy from their vehicles to meet upcoming federal regulations but also to support customers who are trying to minimize the impact of fuel costs,” he continues. “This means that an on-road customer may have a choice between normal film thickness or one that is thinner based on the fuel economy performance they are targeting.”

McGeehan adds that it is also “possible that, after testing, on-highway vehicle manufacturers may decide the fuel-economy oil is backward-compatible with their older vehicles. If so, then more fleets may adopt the maximum fuel-economy formulation that has a thinner viscosity film to try and incrementally improve fuel economy performance and help lower their total cost of operation.”

“The new fuel-efficient, heavy-duty engine oil will, by design, provide improvements in fuel economy,” remarks Victor Kersey, technical director for Valvoline Commercial Products. “The degree of improvement will be affected by engine make and model, driving conditions—both driver and duty cycle—and the oil’s ability to maintain fuel efficiency throughout the oil drain interval.

“It will be less challenging to formulate two oils,” he continues. “One will be a fully backward-compatible product with possible traditional viscometrics, such as SAE 15W-40. The second will be a lower-viscosity oil providing fuel economy benefits. Backward-compatibility is unlikely for the 5W-30 lower-HTHS [high temperature/high shear] FE [fuel economy] version.”

“I believe that the technology will exist to do both oil-service categories with the understanding that oil quality will be the driver as opposed to building an oil just to meet minimum specifications,” remarks Mark Betner, Citgo’s product manager-heavy-duty lubricants.


Roll all the expectations together for what PC-11 will have to accomplish and the list of expected improvements to heavy-duty motor oil that Shell’s Arcy touts includes better oxidation stability, aeration, and shear stability; less adhesive wear or “scuffing”; and compatibility with engines running biodiesel blends.

Along with helping meet GHG/MPG targets and continuing to protect engine life and durability, PC-11 will also need to consider concerns raised by engine makers regarding the interaction of motor oil and engine designs as well as the updating of the various engine tests deployed to prove out a new category.

Kersey observes that the need for PC-11 is also driven by the “increased use of biodiesel fuel, engine oil foaming concerns, and improved protection from higher engine operating temperatures.” He says the upshot is “engine oil formulators will be facing several new oil performance tests with PC-11. These are likely to include new oxidation, ring wear, piston scuffing, oil aeration, and viscosity increase tests.”

Chevron’s McGeehan says that some engine tests will be carried over from CJ-4 based on their “current robustness.” He also points out that several tests are being developed for this category along with corresponding test-limit recommendations. “An example of some of the possible new tests under development are the Mack T-13 and Daimler DD13 [Daimler OM 471], which are designed to measure wear and piston liner scuffing, respectively,” McGeehan notes. “However, these tests have not reached the point of development for inclusion into the category-testing program as of this date. The final decision... will be decided by June 2013.”

Lower-viscosity oil grades will appear prominently on the table as PC-11 is investigated and presumably advances, whether to one or two new service categories.

“Engine wear protection with fuel-efficient technology will be a goal [of PC-11],” relates Citgo’s Betner. “We have had fuel-efficient oil technology in the marketplace for some time, however, with excellent results in terms of engine life and engine wear protection.

“There’s no mystery to fuel-efficient [oil] technology,” he continues. “Engine oil viscosity in diesel engines is the key driver to achieving fuel efficiency. If fuel economy is the main driver behind reducing CO2 per ton-mile, then the contribution of engine oil fuel efficiency will be the main component—and again, that will come through [lower] viscosity.

“In my opinion,” Betner adds, “we have the capability and technology to deliver on both [fuel efficiency and engine protection]. It’s a matter of how well this [two-oil scenario] can be introduced to the industry.”

According to Chevron’s McGeehan, moving to lower-viscosity oils “enables fuel economy improvements.” He says that today, 85% of the oils in the marketplace are SAE 15W-40 as API CJ-4 or CI-4 PLUS oils. “Chevron markets lower-viscosity grades, including SAE 5W-30, SAE 5W-40 and SAE 10W-30, that meet API CJ-4 and have fuel economy benefits over our primary SAE 15W-40 viscosity grade,” he notes.

“Currently,” McGeehan adds, “the SAE 10W-30 grade is growing the fastest of all the grades because of its fuel economy benefit and the fact that engine manufacturers such as Volvo, Detroit Diesel and Cummins are now recommending this grade, particularly for 2013 engines, to meet the 2014 fuel economy standards.”


Looking ahead at the challenge of bringing two oil formulations to market, Citgo’s Betner invokes a lesson from the past. “It was difficult for some fleet owners to depart from single-grade oils when SAE 15W-40 was introduced for four-stroke engines. Back in the early ’80s, after making a presentation to a large fleet in an attempt to explain how SAE 15W-40 could help, I was told that 15W-40 would never work in diesel engines. Thirty years later we know how that came out.”

Valvoline’s Kersey says there is concern about the potential for confusion among customers. “The burden will be upon the industry to properly educate end users on viscosity grades, performance levels/API categories, backward-compatibility effects, durability concerns and fuel economy.”

“There are many challenges associated with a new category, especially one with the potential complexity of PC-11,” remarks Chevron’s McGeehan. “For example, the label must be very different for the [resulting] ‘SAE XW-30’ to prevent misapplication. The backward-compatible oil may be named API ‘CK-4’ and the maximum fuel economy formulation could go by another API designation, such as ‘API HD’ oil.”

However the nomenclature is worked out, it will indeed matter greatly to clearly communicate the difference between the two oil categories—if indeed there are two—to all end users of heavy-duty engine oil come 2016.

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