What is Cummins' position on the use of Biodiesel fuel in Cummins engines?
Background
With increased interest in emissions and reducing the use of petroleum distillate based fuels, some governments and regulating bodies are encouraging the use of bio fuels. Biodiesel fuels should be considered experimental at this time. Governmental incentives and/or environmental legislation to use bio fuels may have an impact on the sales and use of Cummins engines. This document outlines Cummins criteria and parameters when using biodiesel fuel.
SME or SOME 'Soy Methyl Ester' Diesel is the most common bio diesel in the U. S. and is derived from soybean oil. Soy Diesel is a biodiesel/petrodiesel blend based on SME. RME 'Rape Methyl Ester' Diesel is the most common biodiesel in Europe and is derived from rapeseed oil. These fuels are collectively known as Fatty Acid Methyl Esters (FAME).
Fuel Characteristics
Biodiesel fuels are methyl/ethyl ester-based oxygenates derived from a broad variety of renewable sources such as vegetable oils, animal fats, and cooking oils. Their properties are similar to diesel fuel, as opposed to gasoline or gaseous fuels, and thus are capable of being used in compression ignition engines. Biodiesel fuels have a lower energy content; about 89% of #2 diesel fuel, and is therefore a less efficient fuel. Its higher viscosity range (1. 9-6. 0 centistokes) vs 1. 3-5. 8 centistokes for diesel) helps offset the lower energy content through reduced barrel/plunger leakage resulting in slightly improved injection efficiency. Combining lower energy content and slightly improved injection efficiency, biodiesel fuel provides 5-7% less energy per gallon compared to diesel fuel. The cetane value of biodiesel fuel is 40 minimum compared to 42 minimum for Cummins diesel fuel specification. Biodiesel fuel has improved lubricity compared to standard diesel fuel.
There are provisional specifications for FAME issued in Germany under DIN V 51 606, and also recently through ASTM PS-121, however these standards are under development and are subject to change. For additional information, refer to the Cummins diesel fuel specifications listed in Table 1 and to the ASTM provisional specification PS-121 for biodiesel fuels.
Emissions
It is the responsibility of the user to obtain the proper local, regional, and/or national exemptions required for the use of biodiesel in any emissions regulated Cummins engine. From the Comprehensive Health and Environmental Effects testing, a fuel blend consisting of 20% biodiesel and 80% diesel fuel (B20) can yield percent reductions ranging from 16-33% in particulates, 11-25% in Carbon Monoxide (CO), and 19-32% in Hydrocarbon (HC) emissions. The B20 biodiesel fuel blend will cause an increase in NOx of 2%.
Performance and Durability Results
Cummins test data on the operating effects of biodiesel fuels indicates that typically smoke, power, and fuel economy are all reduced. However, as there are no firm industry standards on the content and properties for bio fuels, consistency and predictability of biodiesel operation is not well documented.
Biodiesel provides approximately 5-7% less energy per gallon of fuel when compared to distillate fuels. To avoid engine problems when the engine is converted back to 100% distillate diesel fuel, do not change the engine rating to compensate for the power loss when operated with biodiesel fuels.
Elastomer compatibility with bio diesel is still being monitored. The condition of seals, hoses, gaskets, and wire coatings should be monitored regularly.
Cummins certifies its engines using the prescribed EPA and European Certification Fuels. Cummins does not certify engines on any other fuel. It is the user's responsibility to use the correct fuel as recommended by the manufacturer and allowed by EPA or other local regulatory agencies. In the United States, the EPA allows use of only registered fuels for on-highway applications. The EPA has additional alternative fuel information at:
http://www.epa.gov/otaq/consumer/fuels/altfuels/altfuels.htm
Given the current industry understanding of bio fuels and blending with quality diesel fuel, it would be expected that blending up to a 5% volume concentration should not cause serious problems. For customers intent on blending bio fuels above a 5% volume concentration, the following concerns represent what is currently known in the industry. Concentrations beyond 5% by volume could have an adverse effect on the engine's performance and the fuel system integrity/durability. The affects are more serious with increasing concentration levels.
Areas of concern when operating with biodiesel fuels include low temperature operability (fuel gelation, filter plugging), heat content (poor fuel economy), and storage and thermal stability (filter plugging, injector deposits). The oil change interval can be affected by the use of biodiesel fuels and some applications may require shortening intervals to half of the diesel equivalent. Lube oil dilution in applications with significant part load operation will fall under this guideline.
In addition, from Cummins' fuel systems suppliers, the following issues are also noted: swelling and hardening/cracking of some elastomer seals within the fuel system/engine, corrosion of fuel system and engine hardware - especially aluminum and zinc, solid particle blockage of fuel nozzles and passages, filter plugging, injector coking, higher injection pressures due to physical flow properties - reduced fuel system life, added stress and heat to injection components - especially rotary fuel pumps - increased pump seizures and early life failures, poor fuel spray atomization - reduced fuel economy. Pure biodiesel fuel is not stable and its acid content increases over time which can damage powder metal components
Attention: TDR Forum Junkies 
Was it during winter months that you tried the b20? It's possible they either blended with really poor dino diesel, or had a bad batch. Thats the first of hundreds of people I"ve ever heard of having poor running conditions. Must have been a bad batch.
