December 01

Winterizing Diesel Fuel

Winterizing diesel fuel should be considered a top priority if you operate in the northern portion of the United States. Diesel turns into a gel-like substance that will not flow through your fuel system at specific temperatures. Not only will it gel in your tanks, fuel lines, and fuel filter, it can stop you from operating your truck correctly.


Finding a specific temperature for diesel gels isn’t easy because many variables come into play. The two concerning temperature points are:

  • Cloud Point – the point at which paraffin wax begins to precipitate out of the fuel. The fuel will become cloudy, but the actual temperature can vary somewhat.
  • Pour Point – the point at which wax precipitates out of the fuel that it no longer flows. The gel point is generally ten to fifteen degrees below the cloud point.

Different Types Of Oil

All petrodiesel contains paraffin waxes, and it’s these waxes that become solid at lower temperatures. The amount of paraffin wax in your diesel depends on the crude oil used and the process of manufacturing the fuel. Crude oil classifies as:

  • Brent Blend
  • West Texas Intermediate
  • OPEC Reference Basket
  • Dubai Crude

Diesel Fuel Blends

Diesel fuel comes in two blends – summer and winter. Summer blend diesel is non-treated diesel and causes the paraffin wax to begin precipitating out as the temperature drops. Summer blend diesel will cloud and gel at higher temperatures than winter blends mixed with diesel/kerosene. It is the kerosene that lowers the gel point in winter blend diesel. The higher the kerosene content, the lower the gel point.


If you are fueling in a part of the country that is running a petrodiesel/biodiesel blend, you must know that biodiesel will gel at a higher temperature. Like petrodiesel, the approximate temperature at which pure biodiesel will gel depends on the oil it’s made. A petro/biodiesel mix will have a lower gel point than pure biodiesel. Similarly to petrodiesel, a petro/biodiesel mix can be treated to lower the gel point.

Water In Diesel

All diesel has water suspended in the solution from condensation inside a cold fuel tank with warm fuel. You can also get condensation from temperature and humidity changes. Keeping your diesel as “dry” as possible by using a water separator is an excellent way to pull the water out of your fuel.

Diesel Clogging & Gelling

There are several ways to prevent diesel from clouding and gelling. The most common is to add a winter fuel additive. There are additives to address the moisture content by helping to “dry” the fuel and additives that lower the gel point of diesel fuel. Some additives will thaw your diesel after it has gelled.

Winterizing diesel fuel keeps you on the road. Make sure you prepare ahead of time. If you operate your semi-truck in cold climates, it might be wise to treat your fuel. It’s possible to buy fuel in a relatively warm climate in the morning and finish your day in a cold environment. Be prepared and proactive in keeping your diesel flowing.

Source: ATBS