There are at least three ways to run a diesel motor on biofuel utilizing vegetable oils, animal fats or both. All three are utilized with both fresh and pre-owned oils.

1. Use the oil simply as it is-- typically 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 gasoline;

3. it to biodiesel.

The very first two techniques sound easiest, but, as so often in life, it's not rather that basic.

1. Mixing it

Vegetable oil is a lot more viscous (thicker) than either petro-diesel or biodiesel. The purpose of mixing it or mixing it with other fuels is to decrease 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 (same as # 1 diesel) you're still utilizing fossilfuel-- cleaner than many, but still not clean enough, many would say. Still, for every single gallon of

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

People use numerous blends, varying from 10% grease and 90% petro-diesel to 90% vegetable oil and 10% petro-diesel. Some people simply utilize it that way, launch and go, without pre-heating it (that makes veg-oil much thinner), or even use 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 tough and tolerant motor-- it won't like it but you probably won't kill it. Otherwise, it's not wise.

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

Blends with various solvents and/or with unleaded gasoline are "speculative at finest", little or absolutely nothing is understood about their effects on the combustion attributes of the fuel or their long-term effects 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 characteristics from the petroleum diesel fuel for which diesel engines and their fuel systems are designed.

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

They are difficult but they'll just take so much abuse. There's no guarantee of it, however utilizing a blend of approximately 20% veg-oil of good quality is said to be safe enough for older diesels, especially in summer season.

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

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