The Basics On How Diesel Becomes Contaminated!
 

The latest new government standards require diesel fuel to contain no more than 15 parts per million of sulfur. (ULSD) Refiners meet the new standard by changing the way they refine the fuel. (hydrotreating) When initially refined it is a cleaner more pure fuel with a very low free water content. However this new method can increase the suspended water content of the fuel by as much as ten (10) times. Free water is water that separated from the fuel and settles to the bottom while suspended water is suspended in the fuel, invisible to the eye and burns with the fuel. Therefore when the fuel begins to deteriorate (30-90 days) it will release significantly increased amounts of water which in turn produces much more contamination than ever before.  Our techs have seen a big increase in microbial growth. (commonly referred to as algae) 

Another factor that adds to the problem is that before the fuel reaches the consumer pump it may be transferred from three to six storage tanks and or trucks. At every point along the way the fuel usually absorbs small amounts of water and contamination. Once the contamination process has begun it will quickly accelerate while being stored. The water will immediately start to grow microbes, which turns into a rapidly growing colony.  

The colony produces acids that corrode metal parts in the tank and fuel system. The first signs of a problem usually shows up as small but increasing amounts of water and or black granules similar to coffee grinds in the filter/water separator bowl. Bare in mind the fuel pick up tube is 2-6 inches from the bottom of the tank so if you are picking up any water at all there is probably several quarts or gallons in the bottom of the tank. Advanced stages will cause the fuel to be significantly darker in color and take on a foul smell. It will then cause jet black filter elements and or a milky slime with stringy elements resembling spaghetti. If you see this sort of evidence you have an advanced problem that could soon suddenly damage injectors and fuel pumps.  

If not treated immediately the colony will grow very rapidly and can produce several pounds of sludge per week. Warm humid conditions accelerate the process and aggravate the problem even more. Warmer climates magnify the problems.  Most boaters who are aware of the problem typically use a biocide to effectively kill the organisms but that alone will not eliminate the contamination problem.  The bacteria skeletons, along with dirt, rust and water will form thick sludge in the bottom of the tank and when agitated while underway will be sucked into the filter(s) and engine. 

The most economical solution for this condition after it has happened is to have your fuel filtered and purified and the tank(s) chemically cleaned. Fuel polishing or filtering alone does not remove the build-up on the tank(s) bottom and sidewalls therefore a typical fuel polishing/filtering job is a short-term temporary fix and the problem will usually reoccur within 60-90 days.

As with virtually all new fuels the ultra low sulfur diesel is a double edged sword. The negatives include less storage stability, a decrease in power, lower fuel economy, increased static discharge, lower lubricity and can cause seals to leak. However, it also burns much cleaner and can extend the time between oil changes. The biggest positive is the new diesel will now enable American auto makers to finally meet EPA clean air standards with newly designed diesel engines in light trucks and cars that get 35-55 MPG and last much longer than gasoline engines.

What about the new E-Diesel?

(Ethanol blended diesel)

Many racing enthusiast are currently using E-diesel also referred to as OXY-diesel for racing trucks, tractors and even some offshore boats. E-diesel has very limited available for street use at this time. E-diesel users will experience essentially the same problems presented by E-10 blended ethanol gasoline plus a few more.

(See the Ethanol basics page for details) 

 In the 1980’s we experimented with many formulas of e-diesel by combining blends of anhydrous (less than ½ % water) Ethanol, Methanol, kerosene, synthetic oils and diesel fuel in various concentrations. In our experience ethanol/methanol blended diesel actually decreased power in stock production engines. Trial and error finally produced several formulas that increased power in highly modified diesel racing engines.

We do not recommend the practice of custom blending E-diesel fuel for street or recreational use. It poses a potential health hazard and can severely damage or totally destroy expensive engines.

The E-diesel fuel currently available to the public for street use is usually a blend of 10-15% ethanol with an additional 5-10% additive package and 80% #2 diesel. The ethanol in E-diesel has a very powerful detergent action plus it can attack and deteriorate, hoses, gaskets, and fuel pump components just like ethanol gasoline blends. (Clogs filters and injectors)

In addition it will significantly raise the flash (ignition) point of diesel creating a much higher explosion potential. It also alters the cold weather characteristics of diesel, lowering the cloud point and increases the gelling potential.  At this time some diesel engine warranties specifically prohibit use of E-diesel so before you try it check your warranty. (Cummings)

Unlike ethanol-blended E10 gasoline E-diesel is relatively new and not well researched. Several companies are experimenting with E-diesel to try overcoming some of these problems and expose potential new ones. However until the engine manufacturers get behind the effort and modify engine components for compatibility it’s use will be very limited. Currently the most positive feature of E-diesel is a dramatic reduction in emissions. (Air-pollution).

In our experience the bottom line for E-diesel when used in stock street engines is a significant reduction in power and fuel economy, potential fuel system component failures and an elevated explosion hazard. There aren’t many positives here for a fuel some view as a potential improvement.

We firmly believe E-diesel will quickly evolve and many of these problems will be solved. The government will likely mandate its use in the future. However due to it’s higher complexity and the current shortage of ethanol it will likely be years before it is widely used.

Article by Tim Dutcher, USA Fuel Service
www.usafuelservice.com  
© All rights reserved, Tim Dutcher, 2006