Diesel Treatment for Cold Weather

Cold weather is finally here. When the temperatures drop to freezing or below, I start to see a lot of customers buying various treatments for their diesel vehicles and storage tanks. I took care of the company vehicles and storage tanks back in October -- it's easier to prepare than to repair -- but some folks just have to put things off until it's an emergency so they have a reason to complain and panic.

Cold Weather Diesel Problems
Once it gets cold enough, diesel fuel will "gel", meaning that the components of the fuel will solidify and fall out of suspension. Normal #2 diesel has a fair percentage of paraffin wax as a component which solidifies easily. Solid wax doesn't flow, so fuel lines and filters tend to get blocked and fuel pumps have a hard time moving it through the injectors. This means that a cold diesel engine won't start or won't stay running once the fuel starts to gel.

The exact temperature of "cold enough" will vary with the grade of fuel, so in the winter most sellers will either switch to the more expensive, wax-free, #1 diesel (kerosene), or they will blend their #2 diesel about 60/40 with #1 diesel to keep the price down while still being able to pump it.*

Lets look at a few of the problem points of #2 diesel.

Cloud Point
At about 32°F, diesel fuel starts to get cloudy due to the wax starting to form solid crystals. Cloudy fuel will flow through pumps and pipes, but will start to plug filters unless those filters are kept warm. Engine efficiency will suffer and fuel mileage will drop because the fuel system is struggling to move enough fuel.

Cold Filter Plug Point
Since a fuel filter is designed to trap particles, once the wax starts to solidify it will get trapped in and blind off the filter. #2 diesel hits this point at about 15°F and engines start to stall... if they'll start at all.

Pour Point
Once the temperature drops down to 0°F, the wax will have gelled to a point that the fuel will no longer flow (or pour). No fuel means an engine will not run.

Fuel Treatment

This is what we have on the shelf at work and can be found in most truck stops.

The white bottles on the left are Power Service diesel supplement. It provides good anti-gelling and stabilizes the fuel for storage, and a one-quart bottle will treat up to 100 gallons of fuel. This is my choice for my diesel truck with a 50 gallon fuel tank.

The red bottles are Power Service 911, and that is used to fix already gelled fuel. The normal method is to remove the fuel filter and pour the 911 into the canister, where it can dissolve the congealed wax and allow fuel flow. The rest of the container, or another one, is dumped into the fuel tank and left to sit for an hour or two so it can do the same to the fuel there.

The clear bottles of brown liquid are Howes Diesel Treat, our best seller. Howes does everything that the Power Serve does, but backs it up with a guarantee that if you run six bottles of it through your equipment and it still gels, they will pay for the tow to get you fixed up. The two-quart bottles shown will treat up to 320 gallons of fuel, which is easier to use in storage tanks and commercial vehicles with large fuel tanks.


If you have a diesel generator or vehicle, winter can make life more difficult. Keep them warm if you can and treat your fuel so they will start when you need them.


* As a point of interest, home heating oil is basically #3 diesel and has even more wax content. This provides more heat per gallon, but gels up faster if unheated.