One of the questions that biodiesel makers often hear is, “Can’t I just use straight vegetable oil in my diesel engine or furnace?” Â Actually, most of us in the business have asked that question ourselves or even tinkered around trying to make it work. Â So if you’re interested in trying veggie oil, here are some tips and resources that may be helpful.
The US Department of Energy has tried a lot of things in a lot of ways. Â There have been billions and billions of dollars spent on experimentation, studies and trials. Â Thousands of pages of scholarly articles out there summarize their work but are pretty difficult to decipher. Â So we were grateful when the DOE issued an easy-to-read fact sheet on a topic like using veggie oil in diesel engines.
It turns out that the answer is, “yes, but…”.
Be prepared to carefully study the blend percentage of SVO to be mixed with diesel and be prepared for some unwanted side effects. Â The DOE reports that coking (build-up of carbon) is the primary side effect of SVO in diesel engines. Â If you blend less than 5% you will see long term negative impacts on the engine but should not expect immediate catastrophic damage. Â On the other hand, if you go large right out of the gate, then expect carbon to be building up on the valves and pistons until you can’t run the engine any longer. Â Carbon is abrasive and will tear up your engine quickly. Â So, like most good things in life, a little may be okay but a lot will sink you. Â Even Rudolf Diesel studied the concept of using SVO in his early diesel engines (see Happy Birthday Rudolf!).
Take a look at http://www.afdc.energy.gov/uploads/publication/54762.pdf.  The fact sheet describes the downsides of using SVO and briefly shows what you can expect at different percentages.  This type of info is practical- it doesn’t say “no, you can’t do that”.  But buyer be warned.  You will see negative side effects.  Know what you’re getting into; do your homework and then decide if you should try it.  If so, monitor the engine and fuel closely so that you learn from it.