Video: Understanding Fuel Contamination

Since when has fuel needed conditioning? It’s a question we’ve heard time and time again. It used to be fine to store diesel for 20 years and it worked perfectly. But since 2011, diesel became a blend of petrochemical diesel and FAME, a biological element that reduces the environmental damage caused by burning the fuel.

Our short video explains why fuel becomes contaminated and what can happen if the issue is ignored.

IPU’s Introduction to Fuel Contamination

Why does fuel need conditioning?

The diesel we now buy is made up of 93% petrochemical diesel and 7% FAME (Fatty Acid Methyl Ester). FAME is a biodiesel that reduces the damage caused by burning the fuel. Whilst this is great the environment it’s a problem for anyone who stores fuel.

As diesel ages it begins to suffer from three main types of contamination:


Water is the enemy of clean fuel. Modern diesel contains water when it’s manufactured and it attracts more water while it’s stored.

  • water is a contaminant in its own right
  • water is a key ingredient in microbial growth
  • water accelerates contamination from solids like rust

Microbial Growth – Diesel Bug

Microbial growth within a fuel tank is commonly known by the generic term ‘diesel bug’. It forms because biodiesel is the ideal environment for bacteria to grow. It feeds on the nutrients (in the form of hydrocarbons) from the fuel phase and then multiplies in the water phase. Often a visible layer of microbial growth will be visible at the fuel/water interface. This can block filters and cause damage to fuel injectors.

Solid Particulates

Of all the different forms of diesel contamination, solid particulate cause the most obvious risk. Fuel contaminated with dust, grit and rust can again cause filters to become blocked and injectors to become damaged.

It is widely accepted that under normal conditions modern diesel will only remain in a usable condition for 6 to 12 months. After this, fuel begins to degrade and, depending on the type and severity of the contamination, could cause an engine failure.

Thankfully, this doesn’t mean you have to dispose of your fuel twice a year. If you introduce a comprehensive fuel conditioning programme you can store it for much longer. To find out more simply use this link.