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

1. Use the oil simply as it is-- typically called SVO fuel (straight grease);

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

3. Convert it to biodiesel.

The very first 2 methods sound most convenient, however, as so typically in life, it's not rather that basic.

1. Mixing it

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

If you're blending veg-oil with petroleum diesel or kerosene (very same as # 1 diesel) you're still utilizing fossilfuel-- cleaner than most, but still not clean enough, numerous would say. Still, for every single gallon of

grease you use, that's one gallon of fossil-fuel saved, which much less climate-changing carbon in the environment.

People use numerous blends, varying from 10% grease and 90% petro-diesel to 90% veggie oil and 10% petro-diesel. Some individuals simply utilize it that way, begin up and go, without pre-heating it (that makes veg-oil much thinner), or even use pure grease without pre-heating it, which would make it much thinner.

You might get away with it with an older Mercedes 5-cylinder IDI diesel, which is an extremely tough and tolerant motor-- it won't like it but you most likely won't kill it. Otherwise, it's not wise.

To do it correctly you'll need what totals up to an SVO system with fuel pre-heating anyhow, ideally utilizing pure petro-diesel or biodiesel for starts and stops. (See next.) In which case there's no requirement for the blends.

Blends with different solvents and/or with unleaded gas are "experimental at finest", little or nothing is learnt about their effects on the combustion characteristics of the fuel or their long-lasting results on the engine.

Higher viscosity is not the only problem with using veggie oil as fuel. Veg-oil has different chemical homes and combustion characteristics from the petroleum diesel fuel for which diesel motor and their fuel systems are designed.

Diesel engines are state-of-the-art devices with really accurate fuel requirements, especially the more contemporary, cleaner-burning diesels (see The TDI-SVO debate).

They're tough however they'll only take so much abuse. There's no guarantee of it, however using a mix of as much as 20% veg-oil of great quality is said to be safe enough for older diesels, particularly in summertime.

Otherwise utilizing veg-oil fuel requires either an expert SVO solution or biodiesel. Mixes and blends are normally a bad compromise. But blends do have a benefit in winter.

As with biodiesel, some kerosene or winterised petro-diesel fuel blended with straight grease decreases the temperature level at which it begins to gel. (See Using biodiesel in winter season) More about fuel blending and blends.