Protect your Diesel during the winter months

So, why are there two grades of red diesel and what are the differences between them? 


winter grade fuel

Whilst Gas Oil is being used in off-road vehicles and machinery within the UK, it must be manufactured to meet BS 2869 Class A2. There are two seasonal fuels that meet the specification: summer and winter grade fuel. 

Summer grade fuel left in tanks over winter can start to ‘wax’ because of cold and harsh weather. Winter grade fuel contains additives that lower the temperature where fuel would normally begin to wax and helps to protect your fuel and machinery, even in freezing temperatures.

Winter grade fuel can be used all year round, however, summer grade diesel is optimised for only the summer months due to its slightly higher viscosity. We always recommend that our customers take steps to mitigate issues during winter, so in this blog, we will cover the precautions to take when you use gas oil.

How do I know my gas oil meets winter grade standards? 

The cold filter plugging point (CFPP) is used for all European gas oil to measure its resistance to cold temperatures. Laboratory testing involves gradually cooling a sample down and drawing it through a fine mesh filter at every degree Celsius. The temperature at which the filter blocks is the CFPP point, and this figure determines the cold weather performance of the fuel. Winter grade British Standard BS 2869 has a CFPP specification of -12°C maximum.

What causes the wax to form?

All diesel fuel contains paraffin, it is the paraffin content that gives diesel the high cetane number that makes for efficient combustion. Normally, the paraffin is dissolved in the fuel, however, when the weather turns cold, cooling the gas oil left in machinery and vehicles these paraffin molecules start to form crystals and solidify.

If the temperature is low enough, larger crystals form and cause filters to become blocked, in more extreme cases the narrow bore pipework can become blocked, stopping the engine from receiving the fuel it needs.   

How can I tell if my fuel is starting to wax?

If wax crystals have formed in your fuel and has a milky or a cloudy appearance, then this is indicating a wax build-up. You can also notice ‘waxing’ in your agricultural vehicles, for example if your engine is starting to stutter, stall or fails to start.

When is winter grade fuel available? 

Winter grade fuel is available from 15th November to 15th March aligning with the colder months when protecting your gas oil against ‘waxing’ is critical. 

What if I have a large volume of summer-grade fuel left? 

We advise that the entire volume of your tank meets winter specifications. If you have lots of summer-grade gas oil left as winter approaches, you should consider adding an anti-wax additive that will work to prevent wax crystallisation and lower the CFPP of your fuel. You will need to use this product before the cold temperatures hit, otherwise, it will not take effect. If you only need one gas oil delivery a year, use winter-grade fuel and ensure it will last until the following winter season. 

What other precautions can I take to protect my fuel in colder weather?

Fuel storage plays an important role in reducing the formation of paraffin crystals in your gas oil. By insulating your tank, filters and pipelines you can help your fuel stay in good condition during poor weather. 

We offer competitive prices and pride ourselves on delivering high levels of service. At WCF Chandlers we have experience distributing a multitude of fuel types so whatever your commercial or agricultural requirements we will work with you to provide a reliable service to meet your needs. 

For prices and enquiries please call our dedicated commercial team on 01476 584123 or email us at