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

1. Use the oil just 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 gas;

3. Convert it to biodiesel.

The first 2 techniques sound easiest, but, as so typically in life, it's not quite that simple.

1. Mixing it

Grease is a lot more thick (thicker) than either petro-diesel or biodiesel. The purpose of blending it or mixing it with other fuels is to reduce 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 utilizing fossilfuel-- cleaner than most, but still not clean enough, many would say. Still, for every gallon of

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

People utilize various blends, ranging from 10% grease and 90% petro-diesel to 90% vegetable oil and 10% petro-diesel. Some individuals just utilize it that way, launch and go, without pre-heating it (which makes veg-oil much thinner), or perhaps use pure grease 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 really tough and tolerant motor-- it won't like it but you probably will not kill it. Otherwise, it's not smart.

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

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

Higher viscosity is not the only issue with using veggie oil as fuel. Veg-oil has various chemical homes and combustion characteristics from the petroleum diesel fuel for which diesel engines and their fuel systems are designed.

Diesel motor are high-tech machines with very precise fuel requirements, particularly 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 guarantee of it, however utilizing a mix of approximately 20% veg-oil of good quality is said to be safe enough for older diesels, especially in summer.

Otherwise utilizing veg-oil fuel needs either an expert SVO option or biodiesel. Mixes and blends are usually a poor compromise. But mixes do have an advantage in winter.

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