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It’s getting chilly – time to check your fuel and get ready for winter

As I walked out to my van this morning I could feel the autumnal chill in the air. Days are getting shorter, night temperatures are plummeting whilst day temperatures are still in upper teens but it is only going to get colder.

So if you have not done so NOW is really the last time to prepare your fuel for the winter.

All summer your above ground tanks have been heating up in the day, cooling at night causing air in the tank to heat up and then condense as the air cools causing a steady increase in water content in the fuel.

Whilst this is never a good thing, heating oil, like all transport fuels, is hygroscopic as it has a minimum of 5% FAME* in it. FAME readily absorbs water, indeed as much as the FAME content. Water provides food for the microbes in the fuel and exist in the tank. The more water the greater the build-up of bacteria and fungus. The result if left unchecked is that diesel bug occurs.

As the bacteria and fungus increases the effects are:

  • Microbial influenced corrosion on the tank.
  • Build-up of sludge within the tank and bio-film on the sides of the tank.
  • Organic acid build-up where the sludge contacts the tank wall (in metal tanks).
  • Build-up of microbial contamination in fuel delivery systems eg in pump filters, slowing fuel deliveries.
  • Increased engine wear.
  • Corrosive deposits on engine parts (injectors, cylinder linings, piston rings etc).
  • Reduced heat in combustion.
  • Overtime changes in fuel properties occur: Colour, Opacity, thermal stability, cloud point, pour point).
  • Separation of additives from the host fuel – a degree of phase separation between the fuels constituent components starts to occur.


A good article written by DOW Chemical is worth a read at: Click Here


The longer these problems are left the worse it gets until your fuel is so far off specification that is damages engines, fails to be delivered through pumps or corrodes through the bottom of your tank and a fuel spillage occurs. One of these ‘worst case’ incidents will draw your attention to the fuel in your tank! By then too late!

However this may be avoided by testing your fuel. When you do, take the fuel from the tank and NOT the nozzle. Samples taken from the nozzle have already passed through various filters some a fine as 10 micron which will reduce the accuracy of any tests taken.

A fuel test will cost less that £100 to perform and will tell you what condition your fuel is in. If the fuel is off specification various remedial steps may be taken to ensure it is returned to good condition:

Fuel polishing may be done to remove particulate and water content on the fuel and will remove most of the microbial contamination in the fuel with the remainder remove by possible addition of a biocide prior to a fuel polish.

Tank, line cleaning and fuel polishing may be necessary if the tank has a build-up of sludge in the tank and bio-film on the sides of the tank. This means that fuel polishing will not be effective other than for a short period of time as the residual sludge holds water and bacteria and must be removed from the tank. Cleaning the tank can be done remotely or by man entry and at the same time the fuel lines should be cleaned and pump filters changes so that the how fuel delivery system is clean. This operation is best done where fuel levels are low so that the residual fuel can be held in a tanker and be polished before it is put back into the tank.

In summary NOW is the time to have your fuel tested. If you do not the condition of the fuel is ONLY going to get worse and the consequences of that could be costly in terms of unplanned disruption, damage to equipment, fuel spillage caused by tank failure.

LCM is here to help and provides fuel sampling, fuel testing, fuel polishing, tank and fuel line cleaning both remotely and by man entry.

We can send you sample packs so that if you can you can take your own fuel samples. We are also there to provide advice and support.

Contact our Southampton office on 02380 695198 and speak to Stuart Miller-Hall or explore our website for further advice and support.

*FAME – Fatty Acid Methyl Esther.

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