There are at least 3 ways to run a diesel motor on biofuel using veggie oils, animal fats or both. All 3 are used with both fresh and pre-owned 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 mix it with a solvent, or with gasoline;

3. Convert it to biodiesel.

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

1. Mixing it

Vegetable oil is far more thick (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 blending veg-oil with petroleum diesel or kerosene (like # 1 diesel) you're still using fossilfuel-- cleaner than most, however still not tidy enough, lots of would say. Still, for each gallon of

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

People utilize different mixes, varying from 10% veggie oil and 90% petro-diesel to 90% grease and 10% petro-diesel. Some people simply utilize it that method, launch and go, without pre-heating it (that makes veg-oil much thinner), and even use pure vegetable 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 hard and tolerant motor-- it won't like it but you most likely won't eliminate it. Otherwise, it's not wise.

To do it correctly 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 need for the blends.

Blends with different solvents and/or with unleaded fuel are "speculative at best", little or absolutely nothing is understood about their impacts on the combustion characteristics of the fuel or their long-lasting results on the engine.

Higher viscosity is not the only problem with utilizing veggie oil as fuel. Veg-oil has different chemical properties and combustion characteristics from the petroleum diesel fuel for which diesel engines and their fuel systems are created.

Diesel motor are high-tech machines with really precise fuel requirements, especially the more contemporary, cleaner-burning diesels (see The TDI-SVO controversy).

They are difficult but they'll only take so much abuse. There's no warranty of it, but using a blend of up to 20% veg-oil of excellent quality is said to be safe enough for older diesels, especially in summer season.

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

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