This month, ExxonMobil will announce two motor oils formulated to meet the latest American Petroleum Institute (API) heavy-duty engine oil classification, CI-4, which was developed to ensure proper performance of diesel engines equipped with exhaust gas recirculation (EGR) as well as all engines covered by earlier API four-stroke cycle diesel specs.
Coming on the market this year, diesel engines with EGR were developed specifically to meet the stricter federal diesel-emissions standards that become effective in October.
According to Tom Dietz, both Mobil Delvac 1300 Super 15W-40 and Exxon XD-3 EXTRA 15W-40 will be the first of the company's products to meet CI-4. And like all other CI-4 products, they will be “backward-compatible,” meaning they will be just as effective in earlier, non-EGR engines.
“We will see the majority of our customers moving quickly from CH-4 to CI-4 oil to avoid the complexity of maintaining two different oils in their fleet inventory,” Dietz remarks. “In effect, CH-4 will disappear, as CG-4 did before it.
“However,” he continues, “no one can place the CI-4 designation within the API donut on the oil can label until September 5th. That's to ensure a level playing field to allow all oil marketers to compete in the marketplace with the same performance spec on their products.”
STARTING POINT
But according to Dietz, the API spec is just a starting point. That is to say, ExxonMobil's formulations to meet or exceed CI-4 will be unique.
“We feel that as a company in the lube business for over 135 years we have a huge responsibility to customers,” he states. “What it really comes down to is the product and the support you put behind it in the lab and in the field.”
In the case of formulating oil for EGR engines, Dietz reports that ExxonMobil focused its in-house efforts especially on three key areas related to the addition of EGR: higher oil temperatures (which increase oxidation), soot dispersion and rapid TBN depletion.
He is particularly excited over how ExxonMobil lube scientists “broke through a ceiling” by developing a new patented additive component that boosts the effective TBN by a factor of two without actually increasing the TBN number.
“Rapid TBN depletion impacts both soft and hard metals within the engine,” Dietz points out. “But you can't just throw in more TBN because that would increase the ash level. What we've done enables us to get the desirable characteristics of a 14-TBN oil designed into our exclusive 12-TBN formulation.
“The challenge with working with most additive components,” he adds, “is managing the tradeoffs. It can feel like you're trying to balance an elephant on a plate atop a ball. Simply put, it's very challenging to put these formulations together.”
Dietz says that's why ExxonMobil maintains extensive lube testing and development facilities. “We have 12 formulation scientists on staff dedicated solely to commercial lubricant development,” he points out. “And we've invested heavily in engine test cells to run both standard and our own proprietary tests. We also do cooperative research with the engine OEMs,” Dietz notes.
“We've done a lot of work to stay out in front with our lubricant formulations,” he sums up. “And we intend to stay there, especially given the challenge facing trucking — the '07 diesel emissions requirements that API and the industry will be forced to tackle next.”
Each month this column looks at emerging truck technology issues through the eyes of a leading engineer.
