There are at least three methods to run a diesel engine on biofuel utilizing vegetable oils, animal fats or both. All 3 are utilized with both fresh and used oils.

1. Use the oil just as it is-- usually called SVO fuel (straight veggie oil);

2. Mix it with kerosene (paraffin) or petroleum diesel fuel, or with biodiesel, or mix it with a solvent, or with gas;

3. Convert it to biodiesel.

The very first 2 techniques sound easiest, however, as so often in life, it's not quite that simple.

1. Mixing it

Vegetable oil is much more thick (thicker) than either petro-diesel or biodiesel. The purpose of mixing it or blending it with other fuels is to lower the viscosity to make it thinner so that it streams more freely through the fuel system into the combustion chamber.

If you're mixing veg-oil with petroleum diesel or kerosene (exact same as # 1 diesel) you're still using fossilfuel-- cleaner than a lot of, however still not tidy enough, many would say. Still, for every single gallon of

vegetable oil you use, that's one gallon of fossil-fuel saved, and that much less climate-changing carbon in the atmosphere.

People utilize numerous mixes, varying from 10% vegetable oil and 90% petro-diesel to 90% vegetable oil and 10% petro-diesel. Some individuals just utilize it that method, start up and go, without pre-heating it (that makes veg-oil much thinner), or even use pure veggie oil without pre-heating it, which would make it much thinner.

You may get away with it with an older Mercedes 5-cylinder IDI diesel, which is a really hard and tolerant motor-- it will not like it but you most likely will not eliminate it. Otherwise, it's not sensible.

To do it appropriately you'll need what amounts to an SVO system with fuel pre-heating anyhow, preferably using pure petro-diesel or biodiesel for starts and stops. (See next.) In which case there's no need for the mixes.

Blends with different solvents and/or with unleaded fuel are "speculative at best", little or absolutely nothing is understood about their results on the combustion characteristics of the fuel or their long-lasting effects on the engine.

Higher viscosity is not the only issue with using vegetable oil as fuel. Veg-oil has various chemical homes and combustion qualities from the petroleum diesel fuel for which diesel engines and their fuel systems are designed.

Diesel motor are modern machines with extremely precise fuel requirements, specifically the more contemporary, cleaner-burning diesels (see The TDI-SVO debate).

They're hard but they'll just take a lot abuse. There's no warranty of it, however using a blend of as much as 20% veg-oil of excellent quality is said to be safe enough for older diesels, specifically in summer.

Otherwise fuel needs either a professional SVO solution or biodiesel. Mixes and blends are normally a poor compromise. But mixes do have a benefit in cold weather.

Similar to biodiesel, some kerosene or winterised petro-diesel fuel combined with straight vegetable oil lowers the temperature at which it starts to gel. (See Using biodiesel in winter) More about fuel mixing and blends.