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

Biodiesel Myth #8 – Biodiesel Emissions Are No Better Than Regular Diesel

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 #8 – Biodiesel Emissions Are No Better Than Regular Diesel

Biodiesel is the only alternative fuel that has completed all the testing requirements of the Clean Air Act. Biodiesel contains oxygen and it burns more completely than diesel fuel, resulting in reduced emissions. All major pollutants are reduced dramatically in biodiesel exhaust (most of them at least 50% for B100), except one—nitrogen oxides (NOx)—and that’s only for blends over B20 (see my post on the subject).  In fact, NOx emissions from biodiesel increase or decrease depending on the engine family and testing procedures. NOx emissions (a contributing factor in the localized formation of smog and ozone) from pure (100%) biodiesel increase on average by 10 percent.  However, biodiesel’s lack of sulfur allows the use of NOx control technologies that cannot be used with conventional diesel. Additionally, some companies have successfully developed additives to reduce NOx emissions in biodiesel blends.  In fact, in certain independent studies using more modern engines than the EPA study have shown that biodiesel use actually reduced NOx emissions.

The most common report when users switch to biodiesel is the noticeable decrease in diesel smoke (the black, sooty clouds). B20 reduces air toxics (the most damaging pollutants for human health) by 20-40%, while B100 reduces them by as much as 90%. Sulfur oxides and sulfates (major contributors to acid rain) are almost completely eliminated. The only caveat is that nitrogen oxide (NOx) emissions can increase up to 10% with B100. If you would like to evaluate this for yourself, see the National Biodiesel Board’s emissions fact sheet.

New diesel technology like the Mercedes BlueTec and the 2009 Jetta TDI eliminate this problem by reducing NOx emissions by 80-90%.

All-in-all, biodiesel offers such a substantial reduction in emissions that it’s frequently used in sensitive areas like national parks and marine habitats. School districts all over the country have also turned to biodiesel as a way to reduce children’s’ exposure to toxic diesel exhaust.

Biodiesel Myth #7 – Biodiesel is Just Vegetable Oil

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 #7 – Biodiesel is Just Vegetable Oil

This is one of my favorites, mostly because for a long time the media simply wouldn’t actually spend the 10 minutes online researching the difference between soybean oil and biodiesel to know the difference, and actually perpetuated this myth more than anyone else.

To the layman, I can see why it’s easy to confuse.  Rudolf Diesel first invented his engine to run on Peanut oil, as many reporters accurately claim.  However, the modern engine looks almost nothing like Rudolf Diesel’s engine, and that while it’s true that many modern diesel engines can run straight vegetable oil, almost none do because it’s generally accepted as harmful to the engine in the form of engine coking and fouling.  Using vegetable oil also require significant pre-heating of the fuel and a complicated dual fuel setup which is beyond the scope of this blog article.  See the Elsbett SVO Conversion (which will void your warranty) diagram for an idea of just how complicated these systems can be.  For more information, Google “Diesel SVO Conversions” and you’ll see what I mean.

SVO Conversion Diagram

I’ll say it once more in more simple format: “Straight Vegetable Oil Is Not Biodiesel“.

So, what do biodiesel and straight vegetable oil have in common?  Biodiesel is quite usually made from vegetable oil.  But, in truth, biodiesel can be made from animal fats too, or most any fat, for that matter.  Through a process called transesterification, vegetable oil is stripped and converted into Biodiesel (which is technically called a mono-alkyl ester).  This new chemical, trade named “Biodiesel”, is now more chemically similar to petroleum diesel, and has many of the same characteristics of it’s petroleum cousin.  Biodiesel is registered motor fuel and approved by the EPA as a motor fuel and fuel addative, and has an ASTM standard (D-6751) which must be adhered to in order to sell it as a motor fuel.  This standard has very tight requirements on the composition of the fuel, and the limits on impurities that can exist in that fuel.  Fuel that does not meet the standard cannot be sold as biodiesel for motor fuel use.

Vegetable Oil doesn’t have any of those standards and approvals.   See, vegetable oil is generally used as food. Biodiesel is fuel. More to the point, because SVO is not an approved motor fuel by the EPA, using it will most certainly void the engine warranty.  You can actually see the difference.  The picture below shows straight vegetable oil on the left, and biodiesel on the right.  Both are filtered, clean products that could be used as a motor fuel.  The difference is in the viscosity, gums, combustibility, and cold weather performance.    Which one would you put in your engine?

SVO vs. Biodiesel