B5 Biodiesel


Biodiesel is produced in pure form (100% biodiesel), which is referred to as B100 or Neat Diesel and may be blended with petroleum based fuel in various percentages. For example: A blend containing 5% biodiesel and 95% petroleum based fuel is referred to as a B5 blend.

Concerns Regarding Biodiesel

Kubota Engine America Corporation, along with the Fuel Injection Equipment manufacturers (FIE) has the following concerns regarding the characteristics of biodiesel:

  • Free Methanol
  • Free fatty acids
  • Mono & diglycerides
  • Mono & Oxidation and thermal stability
  • Mono & Alkaline metal compounds
  • Mono & Free glycerin
  • Mono & Dissolved and free water
  • Mono & Total solid impurities

According to a statement produced jointly by the Diesel Fuel Injection Equipment manufacturers, B100 biodiesel has been found to create the potential for the following failures/issues in diesel engines:

  • Corrosion of Fuel Injection Equipment (FIE)
  • Increased injection pressure
  • Low pressure fuel system blockage
  • Elastomeric seal failures
  • Increased dilution and polymerization of engine sump oil
  • Fuel Injector spray hole blockage
  • Pump seizures due to high fuel viscosity at low temperatures

Kubota's Position Regarding The Use Of Biodiesel

Kubota accepts the use of biodiesel in Kubota diesel engines and Kubota diesel powered products only if the fuel meets the following conditions:

  • The maximum of 5%, by volume, biodiesel blended with petroleum based fuel may be used (B5 Blend).
    • Biodiesel may be blended in European diesel fuel according to EN590 specifications and blended in U.S. diesel according to ASTM D975 specifications.
    • Biodiesel used as neat (B100) or as a blend component must meet the minimum requirements provided by EN14214 (EU Standard) or ASTM D6751 (US Standard). B5 blended fuel must also meet EN590 or ASTM D975 specifications.
    • Raw pressed vegetable oils are NOT acceptable for use in any concentration.
  • The producer of the B100 fuel and/or the marketer of the B5 blended diesel must be BQ-9000 certified. Kubota does not recommend local blending of such fuel as it is difficult for local blenders to meet the quality standards above.
  • Users of Kubota Emissions Certified Engines are responsible for obtaining any appropriate local, state and national exemptions required for the use of biodiesel.
  • Tampering with tamper resistant parts of the engine are illegal and against Emissions Regulations. This is the case regardless of the fuel being used and subject to punishment under such rules in affect.

The use of biodiesel does not affect the Kubota warranty for material and workmanship. However, any failures attributed to the use of biodiesel, or any diesel fuel, are not factory defects and will not be covered under Kubota’s warranty.

Recommendations Regarding The Use Of Biodiesel

Enhanced care must be taken, even if the biodiesel meets the said standards above:

  • Biodiesel can attract moisture and may contain higher water content than conventional diesel fuels.
    • Keep storage and vehicle tanks as full as possible to prevent moisture from collecting inside. Ensure all tank caps and covers are installed properly to prevent water from entering.
    • Shorter maintenance intervals, such as cleaning the fuel system and replacing fuel filters and lines, might be required.
    • Kubota strongly recommends using a water separator.
  • Follow the standard Kubota oil change interval for the given engine along with checking the oil level daily prior to starting the engine. Extended oil change interval beyond the standard interval can cause engine damage.
  • Cold weather conditions can lead to fuel system plugging, hard starting and other possible unknown failures. Plugging can include both fuel filters and fuel lines. •Microbial contamination and growth can cause corrosion in the fuel system and premature plugging of the fuel filter.
  • Degradation of the fuel in the supply chain or in the vehicle:
    • Accelerated by the presence of oxygen, water, heat and impurities
    • Biodiesel should not be stored for more than 3-months.
    • Prior to engine storage, the engine should be flushed for a minimum of 30-minutes with petroleum based diesel fuel.
  • If Biodiesel is spilled onto painted surfaces, it should be cleaned off immediately to prevent damage to the painted surface.
  • Biodiesel, by definition is biodegradable, so the higher the concentration of biodiesel in a fuel blend, the more susceptible the fuel is to degradation and engine performance and fuel consumption might be affected. Concentrations of no more than 5% biodiesel are approved to minimize potential corrosion on aluminum, zinc material along with rubber and plastic parts.