Winter fuel readiness 2025: How to protect your fuel operations from cold weather risks

Updated November 2025:  Strategies for preventing diesel gelling and fuel contamination this cold weather season

During cold periods, it is possible for diesel engines to experience starting problems. There can even be issues with engines that are already running. These problems may happen when wax crystals form in the fuel and condensation occurs, this can cause blockages that prevent oil from reaching the engine.

What causes the wax crystals in fuel?

All diesel fuel contains paraffins. The paraffin content gives diesel the high cetane number that makes for efficient combustion.

Normally, the paraffins are dissolved in the fuel. However, when diesel is cooled, these paraffin molecules start to form crystals and solidify. If the temperature is low enough, more and larger crystals can form, which then create a mat on the fuel filter and block it. In severe cases, even the narrow bore pipe work – particularly at bends and unions – may become totally blocked. When this happens, the engine will no longer receive the fuel it needs.

You can tell if paraffins have crystallized in your fuel by their appearance. It might look milky, or there could be a reddish deposit on the bottom of your tank or on the surface of the fuel filter. When the temperature stays low for several days or a spell of extreme weather hits, fuel can experience this crystallization problem.

Water Contamination

Water in the fuel can lead to filter clogging and engine issues. Microbial bacteria, fungi, and algae feed off the water in a tank allowing it to grow at a rapid pace. If the water and microbial matter reach the tank output level, they will enter your machinery and boilers, causing engine performance issues and blocking your filters.

Tank Maintenance

Fuel storage plays an important role in reducing the formation of paraffin crystals in your fuel. Your fuel can be more susceptible to the impact of cold weather if your storage tank is in poor condition or exposed to winds. Before temperatures drop, remember to check your tank for signs of damage like cracks, bulging, and rust. Fixing these issues now will help prevent clogged filters and fuel contamination if bad weather hits.

Wind Exposure 

Exposure to wind can accelerate heat loss and reduce the temperature of the fuel, increasing the likelihood of wax crystals forming. Metal tanks are particularly susceptible to wind chill so it is important to make sure that, where possible, your tank is located in a sheltered area. By insulating your tank, filters and pipelines, facilities, and vehicles, you can help your fuel stay in good condition during poor weather. 

Using additives to prevent fuel problems in winter

If you’re thinking of using additives in your diesel and gas oil to improve its cold weather performance, there are a few crucial points to bear in mind.

Anti-wax additives

Anti-wax additives are designed to improve the winter performance of fuel. The additives work to prevent the formation of wax crystals and allow effective operation at lower temperatures than the fuel specification.

Can you use additives to improve a fuel’s winter performance?

Blending any additives in fuel you already have must be done when the temperature is higher than the cloud point (the point at which crystals form). The additive must also be fully mixed to create a homogenized blend, and any secondary treatment must be pre-diluted and free-flowing. It is typically best practice to consult your supplier if you are thinking of using additives, because uncontrolled additives can cause problems such as haze and water suspension.

Another important point to note is that existing additives may have already exhausted the sensitivity and response of the fuel, making further additive treatment ineffective.

For more information about how and when to winterize your fuel, reach out the team at World Fuel.