A brief technical detail:
"EN590 describes the physical properties that all automotive diesel fuel must meet if it is to be sold in the UK, the rest of the European Union, Croatia, Iceland, Norway and Switzerland.
EN590 and water contamination
Although EN590 covers numerous fuel characteristics, water content is the most relevant measure for fuel maintenance. To comply with EN590, fuel can contain no more than 200mg of water per kg of fuel.
This is an extremely demanding standard. 200mg of water per kg of fuel represents just 0.02% water contamination. Because modern biodiesel blends absorb water naturally (i.e. it is hygroscopic) it is practically impossible to adhere to the standard without using a water extraction process such as a polishing system or regular tank cleaning.
EN590 looks beyond water content
As the table below shows, EN590's requirements include the blending of up to 7% Fatty Acid Methyl Ester (FAME) biodiesel with conventional petrochemical diesel.
Property Unit Lower limit Upper limit
Cetane number 51.0
Sulphur content mg/kg 10.0
Flash point oC Above 55
Carbon residue %m/m 0.30
Ash content %m/m 0.01
Water content mg/kg 200
Total contamination mg/kg 24
Fatty Acid Methyl Ether (FAME) (biodiesel) content % v/v 7
EN590 and engine emissions
EN590 was introduced to coincide with the development of new emissions standards across the European Union. The overall goal has been to reduce the sulphur content of diesel fuel. Sulphur had been used as a lubricant in the fuel. Its role is taken by special additives in ULSD.
Since 2007, diesel that conforms to EN590 has been referred to as Ultra Low Sulphur Diesel (ULSD) in the European Union. The phrase "Ultra Low Sulphur Diesel" is governed by different standards in other parts of the world."
I think you'll find that generally there are two grades used in the UK - One for Summer, the other for Winter and sometimes mixed.
