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ExxonMobil’s diesel formulation saves fuel and cuts emissions

Synergy Diesel Efficient is more than ‘swapping out BTU molecules’ engineer says

ExxonMobil applications engineer Lilo Hurtado with a display of Diesel Synergy Efficient , which improves fuel economy and reduces CO2 and NOx emissions. (Photo Credit: Alan Adler/FreightWaves)

Two years after it went on sale in small test markets in Michigan and Texas, ExxonMobil (NYSE: XOM) and its Synergy Diesel Efficient now adorn fuel canopies at 7,500 retail sites and 425 commercial fuel depots.

The 20% drop in diesel fuel prices could get more truckers to check out the diesel formulation’s benefits compared to a diesel fuel with no additives: 

  • Average 2% better fuel efficiency.
  • Lower oxides of nitrogen (NOx) emissions
  • Elimination of additional fuel additives
  • Cleaner fuel system operation

When diesel prices were soaring, some fleet managers saw less-expensive natural gas as a way to preserve their fuel budgets. But the cost of maintaining a natural gas engine is up to four times higher than a diesel engine.

The opposite is true with Synergy Diesel Efficient. The fuel costs more but the performance benefits even out, or improves the total cost of ownership (TCO).


“We saw that the dynamics of how the fuel system operates and the role that it’s going to play was going to be more and more critical,” ExxonMobil applications engineer Lilo Hurtado told FreightWaves at the NATSO annual conference in February. “We wanted to stay ahead of the market to try and anticipate that and came up with the new fuel.”

While the name Synergy Diesel Efficient may not roll off the tongue, it is an attempt to brand diesel fuel the way lubricants like Shell Rotella or Mobil 1 go to market. 

“When you go from one [fuel] supplier to another, it’s perceived that all you are doing is swapping out the BTU [British Thermal Unit] molecules,” Hurtado said. “We’re offering not just the fuel but also branding commercial sites. Vehicle operators like the fuel and they’re coming back. There’s a lot of word of the mouth in the trucking industry.”

Under pressure


Fuel, once injected into an engine at a pressure of 5,000 pounds per square inch (PSI), is now injected at closer to 40,000 PSI.  

The eight-times-greater pressure matters because this higher performance system places more stress on the fuel and system cleanliness.

In third-party testing, Hurtado said Synergy Diesel Efficient showed a 2% improvement in fuel economy in trucks used every day to make money. The fuel economy improvement meant a similar reduction in CO2 emissions. An unexpected bonus: an 11% reduction in NOx emissions.

Downstream benefits include fewer regenerations of the diesel particulate filter (DPF), which must be periodically flushed. That results in the need for less use of diesel to treat the trapped soot in the DPF, which saves the operator money. 

“We’re making an effort to do something more with the fuel and also be more friendly to the aftertreatment system,” Hurtado said,

California dreaming

Efforts to make diesel engines and diesel fuel more efficient largely fall flat in California, which is seeking to get diesel trucks off its roads by 2035. The state is tightening the screws on diesel emissions and promoting the zero tailpipe emissions of battery electric vehicles.

But California’s goal faces the reality that 1 billion more people will populate the planet by 2040,  doubling global economic output by some estimates. That means more trucks will be needed to haul more stuff. ExxonMobil doubts hybrids and electrics will be sufficient to meet the demand. 


“When I talk to the industry, [diesel] is going to be the one that’s going to be the path forward,” Hurtado said.

California wants alternatives to smog-belching diesel because of “our incredibly poor air quality,” Barbara Riordan, a member of the California Air Resources Board (CARB), told FreightWaves. “In the past, hybrids have been considered a transition, so maybe a hybrid might be considered. [Diesel] is certainly going to be used far less than it ever has before.”

No more self medicating

Diesel mechanics and owner-operators use additives to improve engine performance.

“Our approach is ‘Why make the truck driver a chemist?’” Hurtado said. “We’re offering a fully formulated fuel directly from our terminals. You don’t have to self-medicate so to speak.”

Synergy Diesel Efficient was tested with B5 and is sold with B11 in Illinois and B20 in Texas. The ExxonMobil product reduces filter plugging from biodiesel monoglycerides, Hurtado said.

Matt Van Zanten, general manager of J &H Oil Co. in Wyoming, Michigan, tested Synergy Diesel Efficient with regional carrier Holland Special Delivery. It used the ExxonMobil product in some trucks and standard diesel in others. Synergy Diesel Efficient provided up to 4% better fuel economy.

During the Polar Vortex in January 2019, Van Zanten debated whether to use a cold flow additive. He called Hurtado, who said to let Synergy Diesel Efficient work alone. One J&H customer ignored the advice. The company’s truck engines failed in the minus-25 degree temperatures. Two other customers reported no issues.

“This is an additized diesel fuel that is a completely different product,” Van Zanten told FreightWaves. “It’s given us an edge over our competitors. We’re out of the additive business.”

The price of a gallon of diesel fuel has been sliding amid a glut of crude oil. (Chart: DTS.USA/SONAR/FreightWaves)

Alan Adler

Alan Adler is an award-winning journalist who worked for The Associated Press and the Detroit Free Press. He also spent two decades in domestic and international media relations and executive communications with General Motors.