When formulating CJ-4 oils, lubricant engineers observed strict limits on sulfated ash, phosphorus and sulfur.
Modern equipment – and equipment managers – demand lubes that have improved by leaps and bounds over what they were just a few years ago. That’s particularly true of oils for low-emitting 2007 engines.
Under the hood
One difference in ’07 engines is that they run hotter and need an oil with improved oxidation resistance to prevent thermal breakdown and attendant loss of engine protection. The new engines use higher levels of cooled exhaust-gas recirculation (EGR) to cool peak cylinder temperatures and further reduce oxides of nitrogen (NOx) emissions.
But that increases the amount of heat that must be pulled out of the engine. Even Caterpillar, which so far has relied on its Advanced Combustion Emissions Reduction Technology (ACERT), is using some EGR, although, unlike other systems, exhaust gas is drawn aft of the particulate filter, a process the company calls Clean Gas Induction.
Another difference is that additives used in previous-generation oils for specific purposes – such as detergency, dispersancy and corrosion resistance – can damage diesel particulate filters, which are found on all ’07 engines. So oil suppliers had to impose limits on those additives.
Those limits – according to Dan Arcy, technical marketing manager for Shell Lubricants – are referred to as the “chemical box” that oil suppliers have needed to work within. The box includes much lower levels of sulfated ash, phosphorus and sulfur.
Since those additives were common in CI-4 Plus oils, the easy way to meet the new limits was to reduce their levels. “That’s why CJ-4 is referred to as a ‘low-SAPS oil’,” says Steve Goodier, BP/Castrol’s technical manager. “We’ve had to develop new additives that are effective.”
The price is right?
CJ-4 oils have undergone extensive development and testing, and – according to Jim McGeehan, manager of diesel engine oil for Chevron Global Lubricants, and chairman of the American Petroleum Institute’s Oil Classification Committee – that’s why they cost more, along the lines of 5 to 10 percent more than CI-4 Plus oils. “CJ-4 is the most robust oil category ever,” McGeehan says.
Which begs the question: Is it smarter to stock CJ-4 for newer engines, as well as the old, less expensive grade for older equipment? Oil suppliers are quick to assure operators that there’s no harm in switching over completely to CJ-4, since it’s backward-compatible.
That means the new oil not only will protect ’07 engines without damaging DPFs, but also will perform well in older engines and off-road engines that still may be running on high-sulfur fuel, explains Alex Bolkhovsky, commercial vehicle technical adviser for ExxonMobil.
“The transition to CJ-4 is taking place slowly, mainly because the population of ’07 engines is still small,” says Reginald Dias, director of commercial products for ConocoPhillips Lubricants. “So our customer breakdown is such that we’re making both designations available.”
“Right now, less than five percent of the oil we sell is CJ-4,” says Mark Betner, Citgo’s heavy-duty motor oil manager. “But we expect that to rise fairly quickly as fleets purchase new equipment.”
Indeed, a significant number of heavy-duty fleets already own at least one truck with the new engines. In a CCJ survey last month of about 150 on-highway fleets, 26 percent said they were operating one or more trucks with 2007 engine technology.
It appears that, for the foreseeable future, operators’ needs will vary. For example, “We do have some ’07 engines, but we’re not changing the fleet’s oil type,” says Tom Newby, director of field maintenance for Old Dominion Freight Line, based in Thomasville, N.C. “We’re going to continue with CI-4 Plus.”
On the other hand, “I would choose to run just one oil,” says Darry Stuart, president of DWS Fleet Management Services, based in Wrentham, Mass. “As soon as we’ve got ’07 engines, I’ll switch the entire fleet over to CJ-4. I believe in keeping things simple, and sometimes you have to pay a premium for that.”
Synthetic engine oils have demonstrated much higher resistance to oxidation, or thermal breakdown, than mineral-based oils, and as such, they can be a tool for achieving greatly extended drain intervals.
But synthetics traditionally have been a hard sell from a cost standpoint, since they typically go for about two to three times the price of mineral-based oils. And with engines, you’re also talking about the cost of make-up oil.
For most fleets, synthetic lubes have made more sense in transmissions and drive axles. Make-up oil isn’t (or shouldn’t be) an issue, and they allow factory-approved extended drains and improved warranties.
Most all highway/linehaul applications (transmissions and axles) are filled with synthetic lubricants to take advantage of the extended drain and extended warranty opportunities, says Richard Muth, manager of lubricants for Eaton Truck Components. “When we speak about vocational applications, I would estimate about 70 percent are filled with synthetic,” Muth says.
Mike Pennington, senior director of global marketing communications for ArvinMeritor, agrees with Muth, noting that virtually 100 percent of his company’s transmissions and axles go out the door filled with synthetic gear lube.
Even automatic transmissions can benefit from synthetic fluid. For example, Allison requires a factory-fill of its TranSynd fluid to allow the company’s longer Extended Service Coverage. The fluid, says Allison, also can extend drain intervals by up to 400 percent.
Reportedly, the same synthetic qualities that can save fuel in engines can boost mpg in drivetrains. Roadranger has released the results of recent fuel economy tests that revealed fuel consumption improvements of more than 1 percent with use of the newest generation of Roadranger Synthetic Lubricants for transmissions and axles. The tests, which compared Roadranger synthetic lubricants to traditional synthetic blends and semi-synthetic blends, were performed with two major fleets and a third test at the Southwest Research Institute; all tests conformed to SAE/TMC testing protocols.
As the industry moves toward even lower-emitting 2010 engines, synthetic engine oils probably will become more popular because synthetic base stocks have inherently better thermal stability than mineral-based stocks; they’re not as dependent on additives to resist oxidation. Another benefit of synthetic oils is their cold-flow, or pumpability, characteristics, which makes them popular in cold climates.
More stringent emissions regulations are just around the corner, and it’s certain that lubricants will be along for the ride. Whether they’re synthetic or mineral-based, they probably will be better than ever.