Winter Blend vs Summer Blend Diesel: Why Changing Grade Can Help Combat Fuel Contamination

Tue, Jun 25, 2024

Diesel is diesel, right? Wrong! Diesel fuel actually comes in two grades: summer blend and winter blend. These diesel fuel blends are specifically created to perform optimally in different weather conditions in the colder and warmer months.

So, what makes each fuel blend different and why do you need to use them during the different seasons?

What is winter blend diesel?

Diesel fuel formulated for winter conditions has an additive that prevents wax crystals from forming at low temperatures, making it more resistant to gelling in colder months. Winter blend diesel has a cold filter plugging point (CFPP) of -12°C, which compared to diesel with a high cold filter plugging point, is less likely to clog up vehicle engines if used in winter.

gelled fuel

What is summer blend diesel?

Summer blend diesel has a higher viscosity, which makes it less resistant to gelling in cold temperatures with a cold filter plugging point of -4°C.

Summer blend diesel is generally cheaper than winter blend diesel. This is because of the production process: during crude oil refinement, where more summer-grade diesel is produced, making it more readily available and cost-effective than winter-grade diesel.

When is winter blend diesel available?

Winter grade diesel is generally available from suppliers around November time until March. This ensures that the most optimal blend of fuel is used for the winter season, minimising downtime, and the risk of fuel-related issues like fuel contamination and clogged engines and filters.

Using winter blend fuel all year would not be cost effective. When crude oil is refined, far more summer blend diesel is made, making it cheaper and more available than winter blend diesel fuel.

Using summer blend fuel in tanks and engines when refuelling in winter can cause operational problems to machinery, and mixing summer and winter blend fuel together if you have some left over can deteriorate winter grade diesel which can lead to machinery or equipment failure.

In colder temperatures, fuel faces increased risk of degradation due to exposure below its cloud point, or cold filter plugging point, as mentioned above. The cloud point of diesel is the temperature that wax forms from the paraffin wax solidifying, giving the fuel a cloudy appearance. Solidified paraffin wax can clog filters and negatively impact engine performance.

That being said, winter-blend is not immune to fuel contamination caused by water and other contaminants and therefore the same actions should be taken to prevent these...

How to prevent and fix fuel contamination

diesel bug blocking filter

Unprotected fuel tanks are vulnerable during weather fluctuations, as rapid temperature changes inside the tank can cause condensation, adding to the layer of water beneath the fuel — where diesel bug forms.

A fuel tank filter stops some degree of water and diesel bug sludge from entering your vehicle or machinery but does not remove water from the fuel tank entirely.

A fuel tank water absorber like Aquafighter removes suspended, free, and emulsified water from fuel. This stops diesel bug bacteria forming which if left could cause engine and equipment damage. Aquafighter reduces water content levels in the fuel down to less than 75ppm, exceeding the EN590 diesel fuel standards of 200ppm. It is placed inside the fuel tank through the tank opening and pulled out and disposed of once full and when refuelling.

A fuel circulation system draws the fuel up from the tank through a magnetic conditioner, which breaks down the diesel bug into a size that will pass through a two-stage water and particle filtration process to remove the impurities from the diesel fuel, before being circulated back into the fuel tank, free of nasty sludge.

Fuel polishing cleans contaminated diesel fuel. This service involves removing the fuel from the tank completely and passing it through highly efficient filters to remove contamination. After fuel polishing has been carried out, both the free and emulsified water content will be removed down to the required 200ppm which follows the EN590 quality standards of diesel fuel. The fuel can then be put back into a storage tank to be used for refuelling.

Now that you know what the difference is between the two diesel fuel blends, you can use the correct one at the right time of year and ensure water contamination is dealt with before it causes a serious issue.

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