Biodiesel 101
Biodiesel Blends (up to B5)
Currently, all blends up to B5 have characteristics that are indistinguishable from diesel fuel. Work is underway to include specifications for blends up to B5 in the ASTM D975 standard. Navistar and other engine manufacturers approve of blends up to B5, provided that the two components satisfy current specifications ASTM D6751 and ASTM D975. Quality biodiesel blends up to B5 should not cause engine or fuel system problems.
Biodiesel Blends (B6-B20)
Biodiesel blends B6-B20 have different characteristics than diesel fuel. B20 is most widely used by fleets in the United States, because B20 balances performance, emission levels, costs, and availability. B20 is also the minimum blend level that qualifies as an alternative fuel, in compliance with the Energy Policy act of 1992. Blends lower than B20 are used regionally, depending on favorable tax incentives that vary from state to state.
There is no ASTM standard for B6-20 blends, which makes it difficult for customers to determine the biodiesel blend or if it complies with fuel quality and consistency standards for the blend they are purchasing. The ASTM is working on a standard for B6-20 blends. In the interim, the EMA released a B20 Test Fuel Specification (June 2006) defining characteristics for fuel quality and consistency. Until the ASTM B6-20 standard is issued, the EMA B20 Test Fuel Specification is recommended for users requesting quality and consistency of B20 blends.
The National Biodiesel Board (NBB) has established a biodiesel BQ9000 Quality Management Program to train, certify, and accredit all biodiesel producers and sellers. This program should significantly promote product quality and consistency in the emerging biodiesel industry. See www.nbb.org, for more information.
Biodiesel Blends (over B20)
Navistar does not recommend biodiesel blends higher than B20; higher proportions of biodiesel in the blend can cause problems during engine operation.
Navistar, Inc. understands and supports customer interest in renewable fuel resources used to produce biodiesel fuel and recognizes the rapidly growing biodiesel industry and government incentives. Navistar agrees with the official position of the Engine Manufacturers Association (EMA) on the use of biodiesel fuel. See www.enginemanufacturers.org, for more information.
Recommendations for Use of Biodiesel Blends
Navistar recommends that users of B20 select a BQ-9000 certified fuel supplier and request proof from the supplier that the fuel meets the EMA B20 Test Fuel Specification. Fuels not meeting the EMA specification may cause fuel system deposits, plugged filters, contaminated engine oil, and fuel degradation.
If providers and customers follow correct storage and maintenance procedures for fuel and equipment, blends up to B20 that meet the EMA B20 Test Fuel Specification should perform satisfactorily in International® and International® MaxxForce™ diesel engines.
Navistar recommends the following:
- Storage tanks should be thoroughly cleaned of residue and microbial growth before storing biodiesel fuel and tanks should be inspected periodically for cleanliness. Residue, water or microbial growth will compound in stored biodiesel fuel, causing increased fuel deposits that clog fuel filters prematurely. Adding biocides will reduce microbial growth during storage, but this is not a substitute for cleaning storage tanks.
- Vehicle fuel tanks should be thoroughly cleaned and dried before using biodiesel blends.
- Because biodiesel blends tend to dissolve deposits in fuel tanks and fuel lines, new fuel filters should be installed on used engines, before using biodiesel blends.
- Fuel filters should be changed at half the service interval for the next two fuel filter changes after starting to use biodiesel. After this initial period, maintain the service interval specified in the Engine Operation and Maintenance Manual.
- In cold climate conditions, Navistar recommends that an appropriate fuel heater be installed.
- Water separation from biodiesel fuel blends is more difficult than water separation from diesel fuel. Users should be as careful as possible to prevent water from getting into the fuel system. If possible, an additional fuel filter should be installed in the fuel system to remove water.
- Biodiesel blends should be used within six months of the date of manufacture, because the oxidation stability of biodiesel is lower than diesel fuel.
- If equipment fueled with biodiesel is to be stored for more than three months, the fuel system should be drained, cleaned, and dried.
- The following materials should be monitored if engines operate with biodiesel: natural rubber, butyl rubber, nitrile, copper, tin, and lead. These materials can degrade prematurely and cause deposits that clog fuel lines and filters.
Impact of Biodiesel Blends on Engine Emissions
B20 biodiesel blends are widely used in fleets in non-attainment areas to reduce visible smoke, particulate emissions and diesel exhaust odor. Care should be taken to replace and upgrade fuel system seals and gaskets that may have degraded. Biodiesel blends can reduce emission levels of HC (hydrocarbons) and CO (carbon monoxide); however, biodiesel blends may somewhat increase emission levels of NOX (oxides of nitrogen) in some engines. Biodiesel blends, used in new, low emissions engines may not significantly affect emissions.
Tests have shown that biodiesel blends help the self-regeneration of the diesel particulate filters. Work is still underway in the industry to establish how biodiesel blends influence the long-term performance and operability of various catalytic systems and whether the ASTM biodiesel specifications are stringent enough to protect the efficiency of these systems.
Warranty Coverage
Navistar unconditionally warrants use of biodiesel blends up to and including B5 blends meeting ASTM D6751 and ASTM D975 specifications. Use of B6-20 blends is at the discretion of the customer/operator and will not automatically void an engine warranty. However, if engine component failure can be directly attributable to use of a B6-B20 blend not provided by a BQ9000 certified fuel supplier, not meeting the EMA B20 Test Fuel Specification or not used per recommendations in this TSI, Navistar may, at its option, deny warranty on the affected engine or engine component.
