How to Fix Gelled Diesel 

Winter can create some serious problems for drivers — slick roads, icy windshields, sluggish fuel pumps, dead batteries, etc. But there is one area where cold weather can be especially problematic for owners, operators, and organizations that use diesel vehicles: gelled fuel

Unlike gasoline, diesel fuel tends to solidify into a gel-like substance when temperatures drop. This is because diesel fuel contains paraffin wax (which is also called petroleum wax), designed to help increase the fuel’s lubrication and optimize engine power and efficiency. Unfortunately, when temperatures drop to around 20°F ( or about -7°C), the wax begins to crystallize and thicken. If left alone, gelled-up diesel can clog fuel filters and lines, lower fuel efficiency, and make the engine difficult or impossible to start.

In other words, if your diesel vehicle isn’t operating as expected or if you’re having trouble starting it during the winter, then gelled fuel may be the problem. But don’t worry; here, we show you how to fix gelled diesel, so you can keep your engines and your business running hot even when everything else starts to freeze over.

How to Prevent Gelled Diesel

Often, the best way to solve a problem is by preventing it from happening in the first place. There are several preventive measures you can take to minimize the risk of gelling in your diesel fuel, such as:

Fuel Up at Winterized Fuel Stations

Fuel stations that provide ‘winterized’ diesel fuel blends during the colder months can help keep diesel fuel from thickening. These blends contain special additives that lower the fuel’s gel point, making it less likely to solidify in cold temperatures. However, the effectiveness of fuel-station blends can vary widely, so it is important to check the quality and reliability of any fuel station you use.

Use an Anti-Gelling Additive

Often, the more effective alternative to trusting winterized fuel stations is doing it yourself, using a fuel additive/conditioner with anti-gelling properties. Anti-gelling additives work by lowering the temperature at which the fuel begins to solidify, breaking up any existing gelled fuel and improving cold-weather performance. Just make sure to choose a high-quality additive that is specifically designed for diesel fuel.

Regularly Replace Your Filters

Replacing fuel filters every winter is another effective preventive measure to avoid gelling in diesel fuel. How quickly fuel begins to gel depends on several factors, one of which is the amount of contaminants in the fuel. Fuel filters are designed to extract many of those contaminants. But as these filters work they get clogged up, decreasing their effectiveness and possibly even releasing contaminants back into the fuel. A clean filter is always a better option to prevent gelling.

Keep the Tanks Full

Finally, perhaps the most straightforward approach is to keep your fuel tanks full. When the tanks are full, there is less air in the tank. Less air means there is less chance of condensation forming and freezing, dropping the temperature of your fuel and potentially leading to gelling. 

With the right anti-gelling additive, a full tank, and a clean fuel filter, even temperatures well below freezing shouldn’t be a problem.

How to Fix Gelled Diesel Using Additives

As mentioned above, high-quality fuel additives not only help prevent gelling; they can also fix diesel that has already begun to solidify. Here’s how:

  1. Pour the additive into the fuel tank
    Although different additives may include more specific directions, a good rule of thumb for using a fuel conditioner to unfreeze diesel fuel is to use a ratio of about 1 ounce of additive for every 10 gallons of fuel already in the tank. So, if there are about 60 gallons of gelled diesel in the fuel tank, then you would need to add 6 ounces of conditioner.
  2. Pour additive onto the filter element
    If your diesel is gelled then your fuel filter is likely also frozen. Remove the filter and use the fuel additive to help it thaw by pouring up to four ounces of fuel additive onto the filter element.
  3. Wait for the additive to work
    Replace the fuel filter and any other parts you may have disassembled and then prime the diesel fuel system. Wait approximately 30-45 minutes and then start the engine as you normally would. Allow the engine to run for a few minutes to heat up and thaw out. 

How to Fix Gelled Diesel Using Temperature Change

If all else fails, you can always let nature take its course by raising the temperature. As the temperature climbs above the fuel’s gel point, the diesel will naturally return to its liquid form. Of course, this may not be an option if you find yourself in the middle of a cold snap and you have somewhere your vehicle needs to be. Still, pushing the vehicle into a garage and surrounding it with electric heaters may get the job done.

Using alcohol as an additive or relying on other DIY methods for warming up a fuel tank can be dangerous, and should be avoided — it’s better to simply wait out the cold than to make things worse by damaging your engine. 

Summit Fleet Has You Covered

A tank of gelled diesel gas can be a major hassle, but it’s not the end of the world. There are ways to bring frozen fuel back up above the gel point by replacing your filters, using an anti-gel additive, keeping your tanks full, or simply allowing the engine to warm up. 

That said, these measures can be time-consuming and costly, especially for fleet owners who have multiple diesel vehicles to maintain. This is where Summit Fleet services come in. Summit Fleet provides well-maintained, top-quality diesel vehicles to help you beat the cold and get your people and products to where they need to be. We handle the maintenance. We ensure that diesel gelling isn’t a problem. And if the temperature starts to drop, we’re here to step in with a properly winterized solution to meet your business needs.

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