Biodiesel: What you need to know

06 January 2023

A picture of a fuel tank being topped up.

We are getting reports of fuel filter blocking issues. Find out what advice is available, what to do if your are affected and what the NFU is doing to help.

With previous issues, the NFU has been working with a group of industry stakeholders and government representatives to address the problem. One output from the working group has been a new upper limit on the number of contaminant particles in fuel supplied to the UK market of 10,000 parts per million or less.

What to do if you've experienced issues

  1. Contact your fuel supplier to make them aware of the problem.
  2. Ensure you are storing fuel on farm in suitable conditions – you can read more in our article What you need to know about red diesel
  3. In order to better understand the scale and extent of any problems we are asking members who have experienced issues to contact NFU CallFirst. Once you've made contact one of our team will be in touch to ask a few questions about the incident. You can see the questions that we'd like to ask here.

What exactly has happened?

The reports are of fuel filters in farm machinery blocking up unusually quickly, needing to be replaced far more frequently than expected.

The substance found to be blocking the filters varies between reports but commonly consists of a black slime or a clear wax.

Affected machinery includes a range of makes and models, costing members both time and money.

What advice is available?

The NFU’s science and regulatory affairs team has a briefing for members providing information on the issue and an update on actions to investigate the causes and solutions. This is available to download at the end of this page.

What is the NFU doing?

The NFU is aware that numerous fuel samples have been tested and the results show that samples are within specification.

We would like to make members aware that, as this is a complex problem, and the exact causes and solutions to the problem are still to be fully identified.

File downloads

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