When winter hits, diesel drivers face one of the most common cold-weather issues: diesel fuel gelling. If your truck won’t start or struggles to run in freezing temperatures, gelled fuel may be to blame. Understanding what causes diesel to gel (and the best ways to prevent it) can keep you on the road and out of trouble.

What Is Diesel Fuel Gelling?

Diesel contains paraffin wax that provides energy density and lubricity. In cold weather, that wax begins to crystallize. As more crystals form, the fuel thickens and eventually loses its ability to flow. This is what’s known as diesel fuel gelling.

The gelling process typically begins at the cloud point (around 20 degrees Fahrenheit for #2 diesel) and worsens until the pour point, where flow becomes restricted. By 10–15 degrees Fahrenheit, untreated fuel can reach the gel point, where it solidifies and blocks filters and fuel lines.

Symptoms Of Fuel Gelling

Recognizing the signs early helps prevent bigger problems. Common symptoms of gelled diesel fuel include:

• A cloudy appearance in your fuel.

• White smoke from the exhaust when accelerating.

• Engine stalling or sputtering at idle.

• A truck that starts but won’t keep running.

If you see these red flags, your diesel is likely gelling and fuel isn’t reaching the combustion chamber. Now, if you’re in the middle of the hot desert and experience these symptoms, the culprit is not cold diesel fuel.

How To Prevent Diesel Fuel From Gelling

There are several strategies to keep diesel fuel flowing in extreme cold:

1. Use Heat Sources

Garages, block heaters, and even work lights can keep your truck warm. While effective, heating solutions require electricity and aren’t always practical when you’re away from home.

2. Blend With Kerosene

Mixing kerosene or #1 diesel lowers the fuel’s gel point. This method works but reduces fuel economy and lubricity, making it less ideal for long-term use.

3. Add A Diesel Fuel Anti-Gel

The most reliable solution is using a diesel fuel additive designed for winter. Preventing fuel gelling is far cheaper than paying for a tow—$80 for a pickup or $500+ for a semi, not to mention downtime. For just a few dollars per tank, you can safeguard your truck with a proven additive.

Best Diesel Anti-Gel Additive For Winter

Products like Hot Shot’s Secret EDT+ Winter Defense and Diesel Winter Anti-Gel prevent wax from clumping and lower the Cold Filter Plugging Point (CFPP) by as much as 40°F. These additives also improve lubricity and cetane, giving your truck more power and protection in freezing weather.

If your fuel has already gelled, Hot Shot’s Secret Diesel Winter Rescue is an emergency formula that thaws gelled fuel and restores flow—something every diesel driver should keep on hand.

If all else fails, move to a warmer climate. Problem solved.