There are at least three ways to run a diesel motor on biofuel utilizing veggie oils, animal fats or both. All three are used with both fresh and secondhand oils.

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

3. Convert it to biodiesel.

The first two techniques sound easiest, however, as so frequently in life, it's not rather that simple.

1. Mixing it

Grease is far more viscous (thicker) than either petro-diesel or biodiesel. The purpose of blending it or blending it with other fuels is to decrease the viscosity to make it thinner so that it flows 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 most, however still not clean enough, many would say. Still, for each gallon of

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

People utilize numerous blends, ranging from 10% grease and 90% petro-diesel to 90% veggie oil and 10% petro-diesel. Some people simply utilize it that method, start up and go, without pre-heating it (that makes veg-oil much thinner), and 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 hard and tolerant motor-- it will not like it however you most likely will not eliminate it. Otherwise, it's not wise.

To do it effectively you'll need what totals up to an SVO system with fuel pre-heating anyhow, preferably utilizing 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 "experimental at finest", little or nothing is understood about their results on the combustion characteristics of the fuel or their long-term effects on the engine.

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

Diesel motor are high-tech devices with extremely exact fuel requirements, especially the more modern-day, cleaner-burning diesels (see The TDI-SVO debate).

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

Otherwise using veg-oil fuel needs either a professional SVO service or biodiesel. Mixes and blends are typically a poor compromise. But mixes do have a benefit in winter.

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