There are at least 3 methods to run a diesel motor on biofuel using vegetable oils, animal fats or both. All three are utilized with both fresh and used oils.

1. Use the oil just as it is-- generally called SVO fuel (straight vegetable oil);

2. Mix it with kerosene (paraffin) or petroleum diesel fuel, or with biodiesel, or blend it with a solvent, or with gas;

3. Convert it to biodiesel.

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

1. Mixing it

Grease is much more thick (thicker) than either petro-diesel or biodiesel. The function of mixing it or mixing it with other fuels is to lower 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 (same as # 1 diesel) you're still utilizing fossilfuel-- cleaner than a lot of, but still unclean enough, many would say. Still, for every gallon of

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

People utilize different mixes, ranging from 10% veggie oil and 90% petro-diesel to 90% grease and 10% petro-diesel. Some individuals simply use it that method, begin up and go, without pre-heating it (which makes veg-oil much thinner), or perhaps use 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 difficult and tolerant motor-- it will not like it but you most likely won't kill it. Otherwise, it's not smart.

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

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

Higher viscosity is not the only problem with using veggie oil 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 created.

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

They are difficult but they'll just take a lot abuse. There's no assurance of it, but utilizing a mix of approximately 20% veg-oil of excellent quality is said to be safe enough for older diesels, particularly in summertime.

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

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