Biodiesel Myth #9 – Biodiesel Will Gel Up My Tank or My Engine

In a multi-part series about biodiesel, this is one of several articles in an attempt to dispel the myths about biodiesel and it’s use in commercial and private diesel engines.

Myth #9 – Biodiesel Will Gel Up My Tank or My Engine in Winter

Most likely, no.  While it’s true the biodiesel has a higher gel point than diesel fuel, the fact is that both petroleum diesel and biodiesel will gel if it gets cold enough.   If it’s not very cold, biodiesel will not gel up at all.

Biodiesel responds to anti-gel treatments in much the same manner as petroleum diesel.  By adding compounds that inhibit wax formations to accumulate, the fuel in effect remains liquid instead of gelling (or waxing) as the temperature decreases.

The temperature at which untreated biodiesel gels is variable, just like it is with untreated petroleum diesel.  The common temperature at which most people will say untreated diesel will begin to gel is 12°F.   The common temperature at which most people agree biodiesel will begin to gel, although it’s largely based upon feedstock so we’re going to assume soy biodiesel, is 30°F.   Adding anti-gel compounds significantly lowers that temperature in both fuels.

Cold Flow Additives Help Any Fuel Blend in Winter

Further, in winter time, diesel fuel not only has anti-gel additives in it, it usually is mixed with #1 Diesel (kerosene) in colder climates.  Kerosene is a light fuel oil, which has a gel point of -30°F.  Adding it in a 1/20 ratio to biodiesel or a biodiesel blend will further winterize your fuel.   However, for most temperate climates, it’s not necessary.  Regular B20 biodiesel (with #2 winter diesel) will work just fine down to about  -5°F.   Always make sure your diesel (and biodiesel) fuel has been winterized in cold weather months, and it wouldn’t hurt to add it yourself just to be sure.  It beats being stranded on the side of the road.

What do you do if the fuel has already gelled in your tank?

You wake up on the morning to go to work and your vehicle will not start.  Your fuel has gelled in the tank overnight.  What do you do?   The time proven remedy is to add a gallon of kerosene for each 10 to 20 gallons of fuel to the tank, then allow it to sit long enough for the kerosene to diffuse into the fuel.  In weather below -20 degrees F, one gallon of kerosene for 10 gallons of fuel will keep things moving, but fuel economy will be reduced because kerosene has a lower BTU value per gallon than #2 diesel fuel.   Block heaters and tank heaters are also added in severe climates to help ensure fuel is flowing.    Store your vehicle in a garage if possible.

For more information, visit the NBB website at

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