What Is Diesel Fuel Gelling? What is Diesel Fuel Gelling?

The engine may not start or turn over if you arrive at your vehicle after a cold night. Sometimes, the problem could be due to diesel fuel gelling.

We explain the reasons diesel fuel gels, and offer some solutions. There are a few options if diesel fuel gels already. 

Diesel Fuel Gelling - What's it?

Gelling of diesel fuel occurs when temperatures fall so low that it turns to a gel substance. Diesel fuel gelling is when the liquid becomes a waxy or gel-like substance.

The engine cannot run diesel fuel that has been gelled. This can lead to severe performance issues that could prevent the vehicle from starting.

Why Does Diesel Fuel Gelling Happen?

Diesel #2 has a reputation for gelling or freezing at 17.5 degrees Fahrenheit. While this diesel fuel costs less at the pump, it’s not a good choice for any vehicle operating in low temperatures. Diesel #1 is known for its low viscosity (and protection against freezing) and it's also called winter diesel. There are many stations that offer diesel #1, which is mixed when it gets colder.

Three stages are involved in the gelling of diesel fuel. The diesel wax begins solidifying at the cloud stage. This is when the diesel fuel turns cloudy. Diesel fuel starts to lose its fluidity at this point. Finally, the diesel fuel hits the gel point when wax crystals form and the fuel can’t be pumped through the lines or filter any longer. 

You will know that the diesel fuel is gelled if the temperatures dropped and your vehicle won’t start. The fuel could cause your vehicle to stop working or it may not start at all. You can check the fuel pressure, if your vehicle is on its own, to determine if there are any problems with gelled diesel. 

How to prevent Diesel Fuel Gelling

Winterized diesel is the best option to avoid diesel fuel gelling. You can also use an anti-gel fuel additive that you add into your tank. It’s also better to keep your fuel tank as full as possible.

Below is more information on how you can prevent diesel fuel from gelling.

1. A Block Heater for In-Place Use

A few diesel cars are fitted with an engine block heat. If you reside in colder climates, this is an essential piece of equipment.

The engine block heater should be turned on at night to prevent the chill from setting in. If you don’t have one, you can get your dealership to install one. 

2. Use Winterized Diesel Fuel

You may have to research winterized fuel if you are looking for it. Don’t assume that every fuel station is offering this type of diesel.

You might have to ask around for the information. Some stations may offer one or the other at a different pump. If you can’t find true winter diesel, at least get a mix that lowers the gel temperature. 

3. Use anti-Gel fuel additives

A variety of fuel additives have been developed by top brands. You should use special additives if fuel gelling is a concern.

Gelling protection can be achieved by using an additive to fuel that's not made from alcohol. Some of them will have additional properties that help to stabilize and clean the fuel.

4. Maintain full fuel tank

It’s important that you keep your fuel tank filled up during colder months. You should always stop at a gas station if you are in an area that doesn't have one.

Diesel will not freeze if there is more fuel in your tank. With a full tank of fuel, less condensation and water can get in the system. This keeps it from gelling. 

5. Parking your vehicle inside

You will make your car more durable by protecting it from the elements. If the temperature drops, store your vehicle in a garage.

If you have a heated garage, that’s even better. Any shelter will change the temperature slightly but it won't stop the diesel gelling. 

Diesel Gels: What Should You Do?

1. Get warm in your vehicle

You must first warm the car up before you do any other work. It is important to warm the vehicle if it starts.

Also, inspect the fuel. You should wear gloves as bacteria can grow in diesel fuel. 

You might be dealing with bigger problems if you can see something that looks like chocolate mousse. It is actually an indicator of microbe growth inside the tank. 

2. Replacing the fuel filter

You should inspect the fuel filter during your inspection. You should take immediate action if you find any waxy or gel-like substance on the fuel filter.

First, drain the water separators. Or you might have to deal with continuing problems, the fuel filter must also be replaced. 

Reported: Five Signs That Your Fuel Filter Is Not Working

3. Get De-Gel products

You can try De-Gel if your diesel is leaking. These are supposed to re-liquefy the diesel but don’t always work. It may be possible to de-ice your fuel filter if you are successful.

Keep in mind that a De-Gel additive isn’t going to prevent gelling from happening, so you shouldn’t use it preemptively. You should instead use Anti-Gel to prevent gelling. 

However, with the proper care and by using the right fuel, you shouldn’t have to worry about your diesel gelling in the first place.