Independent study of 15 diesel pump samples reveals significant differences in fuel quality across the US and Canada
NORTH KINGSTOWN, R.I. — Diesel fuel may carry the same label from one pump to the next, but what’s coming out of the nozzle can vary considerably — and those differences can affect everything from cold-weather performance to engine wear.
That’s the takeaway from a recent study released by Howes Products, which analyzed 15 samples of winterized No. 2 diesel fuel collected from retail pumps across the U.S. and Canada. Testing revealed significant differences in six properties related to fuel performance and reliability.
To ensure the samples reflected real-world fueling conditions, the diesel was collected by a group of independent Howes customers, partners, and industry influencers rather than by company personnel. Participants included Kate Whiting, owner-operator of the iconic 1973 Kenworth W900 “Cherry Pie,” Trucker Josh, a well-known trucking content creator who regularly travels between the U.S. and Canada, and country music artist and professional truck driver Tony Justice.
Samples were collected at various locations in Wisconsin, Tennessee, Kentucky, North Dakota, Minnesota, Texas, Oklahoma, Iowa, Nevada, Rhode Island and Canada.
Putting pump diesel to the test
The samples were tested as received for six key properties that directly affect diesel performance and reliability:
- Cloud Point;
- Cold Filter Plugging Point (CFPP);
- Flash Point;
- Biodiesel Content;
- Water Content; and
- High Frequency Reciprocating Rig (HFRR Lubricity).
The testing revealed considerable variation across all six measurements. Among the findings:
- Cloud Point ranged from +14°F to -38°F, a 52°F difference, highlighting how significantly cold-flow properties can vary from location to location.
- Cold Filter Plugging Point (CFPP) ranged from +9°F to -38°F, a 47°F spread across the samples indicating a wide variance at which fuel may begin to restrict filter flow.
- Flash Point varied from 124.4°F to 142.9°F, reflecting a 14.9% variation across samples.
- Biodiesel content ranged from 0.2% to 6.1% by volume, representing a 2,950% variation across samples in biodiesel concentration.
- Water content ranged from 13.2 ppm to 56.2 ppm, showing a 326% variation across samples.
- HFRR lubricity ranged from 184 to 476 microns, representing a substantial difference in wear scar diameter, a key indicator of fuel lubrication performance.
“Some people think of pump diesel as a single, consistent product,” said Rob Howes II, president of Howes Products. “While many know that’s not true, there are still misconceptions regarding how different diesel can be even from pump to pump in the same area.
“What this testing demonstrates is that diesel fuel can vary considerably from one fueling location to another — and even from one fill-up to the next,” he continued. “Those differences can influence cold-weather performance, fuel system protection and overall vehicle operation.”
Researchers noted that part of the variation in cold-weather performance was expected because several samples had been winterized using #1 ultra-low sulfur diesel (ULSD), a common practice in colder climates. However, even after accounting for winter blending, significant differences remained in lubricity, flash point, water content, and biodiesel concentration.
A closer look at lubricity
One of the study’s most notable findings involved lubricity. Two northern fuel samples exhibited nearly identical cold-flow characteristics and flash points, yet their HFRR lubricity results differed dramatically — 476 microns versus 252 microns. Because a lower HFRR wear scar indicates better lubricity, the results suggest that fuels appearing nearly identical in routine screening can provide substantially different levels of fuel system wear protection.
Differences from pump to pump
The study also found noticeable variation among samples collected by the same driver during routine travel, indicating that fuel chemistry can change from stop to stop rather than simply by geographic region.
Water content, while important for corrosion prevention and cold-weather reliability, did not correspond directly with the poorest lubricity results in this sample set. Likewise, biodiesel was detected in every sample tested, ranging from 0.2% to 6.1%, illustrating that low-level biodiesel blends are now a common part of the diesel fuel landscape. None of the pumps were identified as containing bio blends, further proof diesel drivers can never be certain what’s coming out of the pump.
“The most important takeaway from this study is that diesel fuel should not be viewed as a single, uniform product simply because it carries the same pump label,” said Jed Talbot, chemist at Howes Products. “Fuel composition is influenced by factors such as seasonal blending, biodiesel content, refinery practices, additive packages, storage, and distribution.
“Our results showed that fuels with very similar cold-flow characteristics could still perform very differently in critical areas like lubricity,” he continued. “That’s why understanding fuel variability and taking steps to protect against it is more important today than ever before.”
What the findings mean for drivers
According to Howes, the findings reinforce the importance of understanding that the diesel fuel purchased at retail pumps is not always chemically identical and those differences can influence performance, maintenance requirements, and troubleshooting efforts.
“The label on the pump may stay the same, but the fuel behind that label can be very different,” noted Rob Howes II.
The complete report includes detailed laboratory data, analysis of each fuel property and discussion of how naturally occurring variations in commercially available diesel fuel may affect equipment performance.
Howes says the findings also underscore the value of consistent diesel additive use. The company offers a complete line of additives designed to improve fuel performance and help protect critical engine components from problems associated with today’s ultra-low sulfur diesel (ULSD).
For more details from the test, click here.
Linda Garner-Bunch has been with The Trucker since 2020, picking up the reins as managing editor in 2022. Linda has nearly 40 years of experience in the publishing industry, covering topics from the trucking and automotive industry to employment, real estate, home decor, crafts, cooking, weddings, high school sports — you name it, she’s written about it. She is also an experienced photographer, designer and copy editor who has a heartfelt love for the trucking industry, from the driver’s seat to the C-suite.
