Biodiesel Myth #2 – Biodiesel Requires Engine Modification

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 #2 – Biodiesel Requires Engine Modification

We hear it all the time, “What do I need to do to my car or truck so I can run biodiesel?”

Our response, “Just pour it in your gas tank.”

Really, that’s it.  Unlike E85 ethanol which requires a “Flex Fuel” engine modification in order to burn ethanol, all diesel engines can run biodiesel.  Biodiesel is chemically compatible with diesel fuel, and the diesel engine running it doesn’t know the difference.  There are some minor exceptions to this, but most of them are not applicable to modern diesel engines.

All diesel engines manufactured after 1994 use seals and gaskets made of Viton, a chemical compound which is resistant to solvents in Ultra Low Sulfur Diesel fuel.  Turns out, biodiesel is mildly solvent as well, and Viton also resists biodiesel as well.  But, older diesel engines may still use Buna or Nitrile materials, which can be dissolved by biodiesel (and ULSD for that matter).  The effect can happen quickly with pure B100 biodiesel, sometimes in less than two tankfuls of biodiesel.

The solution is to simply run lower blends of biodiesel.  A B20 or B10 biodiesel blend is generally accepted as being compatible with all diesel engines, regardless of manufacture date.   The long term solution would be to replace the seals and gastkets with Viton, which, for engines made in the early 90’s or before, probably has already been done anyway (and they’re probably Viton!).

Other than the Viton issue, any diesel engine, boiler, or furnace that burns diesel fuel can use biodiesel or biodiesel blends.  No modification necessary.

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