Fuel gelling in winter and how to prevent it

diesel fuel gelling in winter

One very real, and potentially fatal winter driving issue is fuel gelling. When the fuel starts to gel, it blocks the filters and fuel lines, and will kill the engine from fuel starvation, exactly the same way as running out of fuel. The colder the outside temperature, the greater the risk of fuel gelling. The worst-case scenario would be somewhere between Hearst and Longlac at 3 am, in -40°C and the truck shuts down due to gelling. At that temperature, frostbite can set in in about 30 minutes, and hypothermia won’t be too far behind that. In January of 2019, a driver in Minnesota had his engine shut down due to gelling while he was asleep. He never woke up again. It really can happen that fast.  

The best way to prevent fuel gelling, is first and foremost, whenever possible, use #1 diesel. It is refined to prevent, though it may not eliminate fuel gelling. In Canada,

All fuel sold during the winter months is #1 diesel. In the US, save for the northern border states, it’s not even offered for sale. Always carry a ready supply of fuel conditioner. Howe’s makes a great product, and Diesel 911 also works well. Always carry a minimum of 2 jugs. 

Most trucks have heated fuel tanks, which is a bit misleading. The tanks aren’t heated, but the engine draws more fuel than it needs, and what isn’t used is heated by the engine and returns to the tanks. Our trucks are equipped with this feature, but I still carry fuel conditioner. 

fuel vacuum gaugeSome trucks are equipped with a fuel vacuum gauge, like the one pictured. If the gauge is registering at 5 or above, you are in serious danger of gelling up. If you do gel up, the only thing you can do, shirt if getting the truck inside to thaw out the fuel, is to change the fuel filters, add at least twice the suggested amount of conditioner, and wait for it to degel the fuel. Trust me, this won’t happen at a well-lit rest area or a truck stop. You will be on a soft, narrow shoulder on a deserted 2 lane bush road at 3 am, and no moon light at all. 

So be mindful of fuel gelling, take every precaution and carry lots of fuel conditioner. You may never need it, but it’s better to have it and not need it, than to not have it and need it!