Low Sulfur vs. High Sulfur Diesel Fuel

Expedition Overland Travelers have a real problem. In fact, we have 2 problems. The 1st is that we don’t know how big of a problem with have with the 2nd problem . . . ULTRA LOW SULFUR DIESEL.

By law, all diesel vehicles manufactured after 2007 are required to use Ultra Low Sulfur Diesel. By law in the U.S. our Ultra Low Sulfur Diesel (ULSD) carries 15 particles per million (ppm) of sulfur for highway use. You may still purchase off-road diesel that ranges from 50 ppm and up. 50 ppm is marked as Low Sulfur Diesel. Countries that do not require ULSD have high-sulfur diesel which can carry as high as 2,000 ppm! I have attended several seminars and discussed this issue with engineers from Cummins, Caterpillar, and Detroit-Mercedes. No one can give an answer as to how long the Particulate Filter itself will last that is being used on all new diesel engines. They have estimated between 150,000 to 300,000 miles on medium-duty truck engines using ULSD, although it has not been tested.

Unless diesel fuel is marked as ULSD or LSD, it is the “old” High-Sulfur diesel. It would not be uncommon in poor countries to have High-Sulfur with as much as 2,000 ppm. The fuel would not have to be refined as much. Most countries are willing to accept this high sulfur content fuel to save on the cost of the product. It does not hurt their vehicles, only the environment, and in fact adds lubrication to the motor itself and allows the motor to run cooler.

This is a real problem to all expedition travelers. The engineers that I have talked to say that there is no solution. Avi Myers from Unicat told me that he has talked to International Truck about the problem, and that they told him that he could disconnect the Particulate Filter and the Catalytic Converter, remove both and replace with a piece of pipe to fill in the gap. Then just ignore the light on the dash. When I talked to International Truck, they told me that this would not be a possible solution. I am hoping that he has, or will, come up with a possible solution, as the European manufacturers have faced this problem longer than the American manufacturers.

Possibly the reason the system cannot be simply removed is that there are at least 3 to 4 probes on the new motors that sense the air quality to the Catalytic Converter and the Particulate Filter. It senses and checks the quality of the air going to the Catalytic Converter, out of the Catalytic Converter, into the Particulate Filter, and out of the Particulate Filter. Some have essentially a dual probe between the Catalytic Converter and the Particulate Filter. The motor sends a electrical signal to the probes. The probes report the air quality back to the motor and the combustion of the motor is manipulated based on the timing and the quantity of the fuel/air mixture in through the combustion chamber to keep the motor running as clean as possible.

Some motors will actually have a sequence that allows the motor to run hot and fast for a very brief period of time. This is essentially the only indication that the system is working to burn out the build-up in these 2 filters. This is called a “re-gen” system. This is found in 2007 and newer Ford diesel trucks. It is this system that is primarily responsible for the increase of fuel consumption. The way this works is that the system when it goes into re-gen mode injects raw diesel fuel directly into the chamber and ignites it within the dual-chambered exhaust system (Catalytic Converter/Particulate Filter). The engineers state that on 15 ppm, the target specification is 150,000 miles before replacement of the Catalytic Converter and Particulate Filter, which is the same 150,000 miles, which is considered the target spec, of medium-duty trucks.

What will happen when the system becomes contaminated to the point that the filter needs to be changed is that it will essentially “plug up” like the old Catalytic converters did in a gasoline car, restricting the exhaust to a point where it will not run. In fact, it will trigger the LOS (Limp Operation Strategy). The LOS limits the power output of the motor and the top speed, and is designed, as the name suggests, to go at a very low speed a limited distance for service. They would not indicate what the distance was, but suggested that you would “immediately” need to find service. You would also have to have the motor hooked to the diagnostics system to re-boot the system and clear the fault code, enabling the motor to act normal again.

The biggest problem with using 3rd world fuels is that you do not know the quality of the fuels or the amounts of sulfur unless it is posted, and it never is – unless it is Low Sulfur Diesel.

If the Filter, on the short end, can be expected to last 150,000 miles using 15 ppm ULSD, then the amount of mileage based on High Sulfur Diesel can be calculated with shocking results!!

Here are some simple calculations for figures. If someone else has a better formula to calculate it, I would love to hear it. This calculation is based on “worst” diesel, which is 2,000 ppm. While no one knows how common 2,000 ppm is, it is available, and it is unregulated in some countries, and it does not take much of it to create a problem.

Let’s assume a life of 150,000 miles for the filter system
Let’s also assume 7 miles per gallon
This gives a total gallons used in 150,000 of 21,428 gallons
21,428 gallons x 15 ppm of contaminants gives a life expectancy of 321,420 units of contaminants
Based on 2,000 ppm fuel, this filteration system would last 160 GALLONS!!

AT 7 mpg, THE RANGE WOULD BE 1,125 MILES!!!

This using simple high-school math. I am SURE there has to be a flaw in this calculation. I would like it, and appreciate it very much, if someone would help show me the flaw. But, if we assume for a moment that the formula is essentially correct, you can easily change a few numbers to see what the performance would be on the various qualities of diesel. The problem, however, is that pumps are not marked. In fact, retailers do not seem to know the quality of diesel going thru their pumps in the U.S., unless it is marked. So how would you know in a country where it is not regulated, such as Mexico.

The current systems will not allow us to world travel without accepting a great deal of risk of being immobilized at the wrong place or at the wrong time.

We encourage everyone to go out and do their own research. Ask the engineers for the engine manufacturers for the information, not a salesperson trying to sell 1 product or another, including us.

I have shared a lot of information here from my research. Some of it may be found to be incorrect. If so, PLEASE email me with any information to substantiate a change, and let’s try to figure out a solution.