Diesel fuel sludging

Diesel fuel tanks are susceptible to contamination by a variety of bugs known as Hydrocarbon Utilizing Micro-organisms. 
  • Vehicles most at risk of contamination are those that have poorly maintained fuel systems, fuel tanks that are subject to water contamination and those that are infrequently used. 
  • Fuel storage facilities are susceptible to infestations too.
  • They enter tanks through vents or during the transport of fuel and form thick, slimy mats that can block fuel systems and produce acids that attack components. 
  • They can rapidly reproduce, with some varieties able to double in number every 20 minutes under the right conditions. 

Warning signs 

  • The most obvious warning sign of an infestation is persistent fuel line and filter blockage. 
  • Other problems can include corrosion and degradation of metal and rubber fuel system components. 


  • Treatment involves draining and steam cleaning of the tank and the addition of a biocide to prevent regrowth. 
  • The use of biocide alone is not recommended, as it can lead to ongoing fuel system blockage by dead cell material. 
  • Oil companies and fuel distributors can assist with the brand names of suitable biocides. 
  • Failure to deal with contaminated or poorly maintained fuel systems or storage facilities will lead to recurring problems

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