There are at least three methods to run a diesel motor on biofuel utilizing veggie oils, animal fats or both. All three are used 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 blend it with a solvent, or with gasoline;

3. Convert it to biodiesel.

The first 2 techniques sound most convenient, but, as so often in life, it's not rather that easy.

1. Mixing it

Vegetable oil is far more thick (thicker) than either petro-diesel or biodiesel. The function of blending it or blending it with other fuels is to decrease 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 using fossilfuel-- cleaner than many, but still unclean enough, many would say. Still, for each gallon of

veggie oil you utilize, that's one gallon of fossil-fuel saved, and that much less climate-changing carbon in the environment.

People utilize various mixes, varying from 10% grease and 90% petro-diesel to 90% grease and 10% petro-diesel. Some people simply utilize it that way, begin up and go, without pre-heating it (that makes veg-oil much thinner), and even utilize 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 very tough and tolerant motor-- it will not like it however you probably won't eliminate it. Otherwise, it's not sensible.

To do it correctly you'll require what amounts 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 need for the mixes.

Blends with numerous solvents and/or with unleaded gasoline are "experimental at best", little or absolutely nothing is learnt about their results on the combustion qualities of the fuel or their long-term results on the engine.

Higher viscosity is not the only problem with using grease as fuel. Veg-oil has different chemical residential or commercial properties and combustion qualities from the petroleum diesel fuel for which diesel engines and their fuel systems are developed.

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

They are difficult however they'll just take a lot abuse. There's no assurance of it, but utilizing a blend of as much as 20% veg-oil of great quality is said to be safe enough for older diesels, particularly in summer.

Otherwise using veg-oil fuel needs either an expert SVO service or biodiesel. Mixes and blends are generally a bad compromise. But blends do have a benefit in cold weather condition.

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