For many operators of heavy equipment and farm machinery, diesel drives their operations at the construction site and in the field. While these large machines come with their own upkeep and maintenance needs, winter adds another variable into the mix because of the fuel the equipment uses.

That’s right, diesel and cold weather aren’t the best match. Once temperatures outside fall to a certain low, about 32 degrees, processes within the diesel itself start to begin that can cause issues if the temperatures continue to drop.

But let’s dive into why this process happens with diesel fuel and what steps equipment owners can take to prevent it from happening – or how to fix the problem if it does.

Gelling: Why it happens with diesel fuel

The reason diesel is prone to gelling all beings with a wax, allied paraffin or petroleum wax, that occurs naturally in No. 2 diesel fuel. At most temperatures this isn’t a problem, but like we said at 32 degree fahrenheit, a process starts to happen that can lead to trouble once it gets colder and that lower temperature is sustained.

At 32 degrees, the waxes in the diesel start to solidify and crystalize. This is when the fuel can take on a cloudy appearance. At about 14 degrees, No. 2 diesel can start to become cloudy, and at 10 to 15 degrees, the waxes will crystallize so much that the liquid becomes more like a gel – hence the term gelling – and can clog fuel supply and fuel filters.

This is known as the gel point, or the temperature at which the diesel fuel is solid and cannot flow through fuel lines. Once that happens, it’s game over for engines. There won’t be enough fuel moving through the machinery or equipment for it to run properly.

Signs diesel has gelled

It should go without saying that nobody wants to deal with the problem of diesel gelling. However, every operator needs to know a couple of the signs that problems could be occurring so they can take further action and get their equipment or machinery’s engines running properly as soon as possible.

The first, most obvious symptom that points toward diesel gelling is that the engine just won’t start. This happens when the fuel has reached the point where it has gelled and clogged up the fuel filter, which in turn has prevented the engine from starting to begin with.

The other symptom to keep an eye out for is differences in fuel rail pressure. Truck drivers can sometimes notice a difference between fuel rail pressure and actual rail pressure when they are trying to accelerate because the fuel is gelling in the truck’s lines. The desired pressure will go up, while the actual pressure stays low.

How to prevent gelling in heavy equipment

Luckily for drivers of heavy construction equipment and farm machinery that must operate continually throughout the year, even in cold winter weather, there are several options that can help keep diesel flowing and engines running as efficiently as possible.

Add a CFI

The first step that can be taken to prevent diesel from gelling is to winterize the diesel fuel you put in your machinery and equipment.

But before we get to the fuel itself, there’s one preliminary step to take, which is to introduce an additive called a cold flow improver (CFI), which is normally effective until about 0 degree. This helps dissolve bonds that cause the paraffin wax and breaks up larger crystals, improving fuel flow.

Use No. 1 diesel gel

Next, you’ll want to consider beginning to add No. 1 diesel fuel. This is due to the fact that No. 1 diesel fuel does not contain paraffin wax.

Now, many states control when fuel stations can switch to these winterized blends, and it’s still not a 100% certain that this will prevent gelling in extreme cold. Still, adding winterized fuel is a good idea.

Cenex advises using a blend of 70 percent No. 2 diesel fuel and 30 percent No. 1 diesel fuel, plus a CFI once temperatures reach a point falling below 35 degrees. From there, go with a blend of 30 percent No. 2 and 70 percent No. 1.

Once the temperature drops below -30 degrees, which is a real possibility in northern climates – and not unheard of, especially when considering wind chills in our hometown of Spencer, Iowa – then it’s time to go straight No. 1 diesel.

Factors to keep in mind

Whenever the weather turns, there are a couple of factors to keep in mind when it comes to diesel engines and cold temperatures.

First, it’s important not to let the engine idle for any amount of time longer than three minutes before you drive it. This is because excessive idling will actually do more damage, even though one might think it’s better to let the engine warm up before driving.

That would be incorrect.

Second, simply take into consideration that it’s harder to start a diesel engine in cold weather. This means that you will want to take precautions listed above, and sometimes add in an extra dose of patience.

Air filters still get dirty in winter

While diesel gelling may be top of mind this winter season, don’t neglect other components of heavy equipment and machinery engines that are also critical to keeping everything running smoothly and efficiently.

As always, it’s a good idea to keep an eye on your equipment’s air filters and to clean them before they get so dirty as to harm fuel efficiency and cause other problems with the engine.

Our Filter Blaster products have been designed to safely and efficiently clean large air filters found in heavy equipment without damaging them. In fact, regularly cleaning the air filter and following other normal maintenance procedures can extend the life of your engine.

The end result? You and your fleet spend more time working and less time sitting idle in a repair shop. The best way to protect your engine: clean it with Filter Blaster.