As we fast approach the cooler months it is important that all our valued customers are aware of the seasonal impact on Gas Oil/Red Diesel and the problems that can arise particularly as the temperatures drop to below freezing point.  This affects off-road vehicles as well as equipment and machinery.

In the UK Gas Oil specifications are set to allow for seasonal temperature adjustments (both of which must be manufactured to BS 2869 Class A2) – Fuel is certified as Summer Grade and Winter Grade.

Summer Grade

Only to be used during this period of warmer months as this grade is only resistant to temperatures of -4°C *CFPP min.

Winter Grade Gas Oil

Whilst the name suggests this should only be used during winter months this grade can be used all year round and will be resistant to colder temperatures down to -12°C *CFPP min.

Problems that may occur during winter if using the incorrect grade of Gas Oil/Red Diesel

In colder periods Diesel powered engines may experience some performance problems in particular when trying to start and often causing an engine to stop.  When Gas Oil/Red Diesel becomes too cold the liquid paraffin molecules within the fuel begin to turn to crystals (the liquid paraffin molecules are designed to dissolve in the fuel) and can solidify and in some cases combine together and form large crystals which block fuel filters resulting in engine failure. When temperatures drop any water that has made its way in to your fuel also has the potential to freeze resulting in filters blocking and engine failure.

Fuel contamination – good housekeeping

It is vital that good housekeeping is maintained wherever you store fuel and the simplest way to protect your fuel is to ensure it is stored correctly. Ideally your fuel tank should be kept under cover or in a protective environment i.e. in a shed as this will assist in protecting against seasonal temperature adjustments providing thermal protection and reducing the risk of water/condensation building up. Simply protecting your tank, pipes, pumps and equipment from the action of wind will also help, whilst not directly effecting the temperature of the fuel it has the effect of accelerating heat loss and therefore more rapid cooling of the fuel.

You should also ensure that you regularly check your fuel for water which may have built up from condensation or via any cracks in the tank itself or pipework etc.  Water in your tank will freeze at 0°C and as mentioned above cause clogging in the filters and pipes.  Water is also prone to attract bacteria which will have a negative impact on your fuel in left untreated.

Summer stocks should be run down before the onset of winter and definitely before your first delivery of winter grade fuel.  If you only have one delivery of fuel a year then always ensure it is winter grade.  Always avoid leaving any summer grade fuel in your tank as we enter winter as this is likely to react abnormally as described above.

Changing fuel filters on a regular basis will ensure a smooth flow of fuel as a blocked filter is less tolerant of tiny paraffin crystals.

How to identify if your fuel has paraffin problems

When Paraffin in fuel crystalizes, you will observe a “milky” appearance.

Fuel Additives

Lynx Fuels provide fuel additives to assist in the improvement of the cold resistance of your fuel and also to treat your fuel should the matter arise, these can be purchased as follows, however please remember that all cases must be evaluated on a case by case basis:

Anti Wax 1L treats 1,000 litres 

Anti Bug Protect 200ml treats 4,000 litres 

Anti Bug Kill 200ml treats 1,000 litres 


Please don’t hesitate to contact the Lynx Fuels Team to discuss any of the above on 01977 455140 or e-mail


  • Do not mix any other petroleum products with your Gas Oil/Red Diesel as this is strictly prohibited
  • Do not heat fuel storage tanks or any part of a vehicle fuel system


*CFPP – Cold Filter Plugging Point Cold filter plugging point (CFPP) is the lowest temperature, expressed in degrees Celsius (°C), at which a given volume of diesel type fuel still passes through a standardized filtration device in a specified time when cooled under certain conditions.  Meaning the lowest temperature at which fuel can be stored.  CFPP is measured in laboratory conditions using EN116 Standard.

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