How to Prevent Diesel Fuel Gelling (Plus Fuel Gelling Symptoms)

It’s hard to believe, but sooner than you think, snow will be covering the ground and the roads will be icy. 

It brings an entirely new set of hazards to driving. 

The freezing temperatures don’t just mean you have to drive differently. It also means you have to take extra precautions with your equipment to ensure it’s running optimally. If you aren’t careful and you don’t take the proper measures, you may end up with fuel gelling problems. 

If your fuel gels, you won’t be hauling freight anytime soon. 

In this article, we’ll help you understand what causes fuel gelling and how you can prevent it with a little extra preparation. 

What is Fuel Gelling? (And its Consequences) 

Before we dig in, what is fuel gelling? 

Let’s go through some definitions. 

Fuel Gelling: Fuel gelling happens in cold weather when the wax in diesel fuel crystalizes and prevents the flow to the engine or clogs fuel lines and/or filters. Paraffin waxes are combustible and help power the engine when burned, but they solidify when temperatures drop. The phases of fuel gelling are listed below.

Cloud Point: The temperature at which wax in the fuel begins to crystallize and form solid particles.

Cold Filter Plugging Point: The temperature at which the engine fuel supply filters become plugged with wax particles.

Pour Point: The temperature at which fuel gels up and will not flow.

Fuel gelling is most prevalent in the winter and it impacts #2 diesel. It leads to performance-related issues in the engine. 

Diesel Fuel Gelling Symptoms 

There really aren’t signs or symptoms that your fuel is about to gel. You won’t notice anything until your fuel has already started to gel, and by then it could be too late. 

Some drivers think black smoke and bad fuel mileage are signs of fuel gelling, but that’s not the case. 

However, there are a few symptoms of fuel gelling that may clue you in to the fact that your fuel has gelled and you need to get it taken care of. For instance, if your engine won’t start or it dies immediately, you might have a fuel gelling problem. 

You may also notice that your acceleration is sluggish and there’s a difference between desired fuel rail pressure and actual rail pressure.

How to Prevent Diesel Fuel Gelling 

Fuel gelling prevention first and foremost begins with fuel type. The number one way to prevent diesel fuel gelling is by properly fueling for the conditions you’re in and treating your fuel. Certain methods you may have heard of, like using fuel line heaters or portable propane heaters are unsafe and not recommended. 

Some drivers may recommend simply idling the truck when temperatures hit below freezing, but that’s not a great idea either. For starters, excessive idling is directly linked to excessive fuel consumption, so not only is it costly, but it also causes wear and tear on your engine and it won’t prevent your fuel from gelling. That’s right: Simply running your engine at all times when it’s cold out won’t help you if you haven’t prepared your tank with the proper fuel. 

As temperatures begin to drop to below freezing, you need to winterize your truck to prepare it for the conditions. Not only do you need to make sure your bunk heater is working, check your tire treads, put your tire chains back in your headache rack and ensure you have the proper winter clothing in your truck, but you also need to make sure you have the tools to treat your fuel to prevent it from gelling.

The first thing you need to do is switch your fuel to a premium winterized diesel with anti-gelling properties. Winterized fuel is specially formulated to prevent fuel gelling and therefore, costly repairs down the road. Many states mandate when stations can start selling winterized fuel blends, so keep this in mind. 

Be mindful of blending of fuel types as you travel from one climate to another. Managing your fuel type purchases for the climate you’ll be in later today and tomorrow is very beneficial. Managing the blend in your tanks will reduce your exposure to costly expenses. 

Fuel gelling can wreak havoc on your fuel system and cause it to fail. The last thing any driver wants is to be left with a truck that won’t start in the dead of winter. Waiting on the side of the road to be towed to a shop for a heat treatment is less than desirable. 

The amount of engine-heated return fuel to your fuel tanks has greatly reduced from previous years’ engines. In the past, an operator could rely on the heated return fuel to reduce the risk of a gelling event, but with today’s engines returning less warm fuel to the tank and all of the no-idling initiatives, you have to plan your fuel purchase. The type of fuel blend or straight product offering will be labeled at the fuel island pumps. The following chart identifies the fuel blending requirements to cope with cold weather conditions. 

Diesel Fuel Gelling Temperature Chart

As you can see in the chart above, at just 5 degrees, the wax in #2 summer fuel will begin to crystallize and form particles. With winters in the midwest seemingly getting longer and colder each year, it’s obvious that you’ll need to blend your fuel every time you’re traveling in states experiencing cold snaps.

But adding winterized fuel to your tanks isn’t enough. You also need to treat your tank with anti-gel additives. Additives lower the temperature at which your fuel reaches pour and gel points and they reduce the formation of crystals. It can improve flowing capabilities and prevent fuel system plugging. 

You should add anti-gelling additives to your tank every time you fill up. The type of additive you use and the current temperature of the area you’re driving in will determine how you need to concentrate your tank. Read the label carefully and add the correct amount to each tank based on the outside temperature and potency of the product. The colder it gets, the more you need to add based on the fuel capacity in each tank. 

You should keep several bottles of anti-gel additives in your truck along with extra fuel filters and an emergency product, like Diesel 911. Certain products can help you if your fuel has gelled and your fuel filter is frozen. It works by reliquefying gelled fuel. However, this shouldn’t be a product you rely on; it should be a last resort. When you use it, it will restore the flow of diesel to your engine so you can start your truck again.

Prepare for Winter Driving Conditions 

It’s not just freezing temperatures, snow and ice you have to deal with in the winter. You aren’t the only one who doesn’t like the cold; your truck doesn’t like it either. To keep it running optimally all winter long (which, in some states, can feel like more than half the year) you have to do some additional preparation.

Fuel gelling is an unfortunate occurrence but you can prevent it by blending your fuel and putting in anti-gelling additives. You’ll be happy you took the extra time to prepare your tank when you see other drivers pulled over on the side of the road waiting for a tow to the shop for a heat treatment.

Visit our article about preventing costly breakdowns to learn more about how to winterize your truck.