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

1. Use the oil just as it is-- generally called SVO fuel (straight vegetable 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 first 2 techniques sound easiest, but, as so often in life, it's not quite that simple.

1. Mixing it

Vegetable oil is a lot more viscous (thicker) than either petro-diesel or biodiesel. The function of blending it or mixing it with other fuels is to decrease the viscosity to make it thinner so that it flows more easily 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 many, but still not clean enough, lots of would say. Still, for every gallon of

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

People use various mixes, varying from 10% grease and 90% petro-diesel to 90% grease and 10% petro-diesel. Some individuals simply utilize it that way, launch and go, without pre-heating it (that makes veg-oil much thinner), and even utilize pure vegetable oil 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 hard and tolerant motor-- it will not like it however you most likely will not eliminate it. Otherwise, it's not sensible.

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

Blends with numerous solvents and/or with unleaded fuel 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 issue with utilizing veggie oil as fuel. Veg-oil has different chemical residential or commercial properties and combustion characteristics from the petroleum diesel fuel for which diesel motor and their fuel systems are created.

Diesel motor are high-tech machines with very accurate fuel requirements, specifically the more modern-day, cleaner-burning diesels (see The TDI-SVO controversy).

They are difficult but they'll just take a lot abuse. There's no guarantee of it, however utilizing a mix of up to 20% veg-oil of great quality is stated to be safe enough for older diesels, especially in summer.

Otherwise utilizing veg-oil fuel needs either a professional SVO solution or biodiesel. Mixes and blends are usually a bad compromise. But mixes do have a benefit in cold weather condition.

Similar to biodiesel, some kerosene or winterised petro-diesel fuel blended with straight veggie oil reduces the temperature level at which it begins to gel. (See Using biodiesel in winter) More about fuel mixing and blends.