As you ought to know, cold weather can create problems for folks who run biodiesel in their vehicles. The B99.9 that Dr. Dan’s is selling should be fine for most of the usual winter weather we experience in the greater Puget Lowlands, but it’s important to remember that prolonged exposure to sub-freezing temperatures can cause the fuel to gel.

There are two important factors to keep in mind: is your vehicle being driven regularly, and what are the 24-hour average temperatures it is being exposed to? Driving your car not only warms up the fuel system, but stirs the fuel in your tank to help keep solids from forming and dropping out of suspension, which can clog your fuel filter. It takes time for biodiesel to gel, and just one cold night won’t necessarily cause problems if you are driving it in the morning. Even parking your car in a spot that gets radiant heat from sunlight can make a difference. It’s also important to keep in mind that trucks tend to be more temperature sensitive than cars because of exposure and unheated fuel components. In cold weather conditions (when the average temperature is below freezing and the ground is frozen solid), you should be proactive and anticipate that the fuel in your vehicle could gel

In the event of gelling, applying heat will reconstitute the fuel. Be aware that repeated attempts to start the engine can eventually draw air into the fuel lines, resulting in a breakdown. Gelling can generally be prevented by blending with petroleum diesel, but “topping off” the tank may not necessarily work, as petro diesel is less dense than biodiesel and won’t mix well at cold temperatures. Again the solution to this potential issue is to drive your vehicle, as this will allow the fuel to blend. It’s also good to remember that a lot of gas stations don’t sell a high volume of diesel, and have inadequate filters on the pump, so it helps to get your petro diesel from higher-volume retailers like truck stops. We also recommend that you use a product like Power Service’s Diesel 911 or Clear Diesel once a year to combat water or bacteria in your fuel tank.

The chemistry of biodiesel can be complicated, and there are no hard and fast rules when it comes to cloud points and cold-start capabilities. Where one user may experience drop-out and a clogged filter, the next may have not an ounce of trouble. As always, if it is going to be below freezing for an extended period of time where you keep your vehicle, take appropriate action.