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

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

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 two approaches sound most convenient, however, 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 purpose of blending it or mixing it with other fuels is to lower the viscosity to make it thinner so that it flows more easily through the fuel system into the combustion chamber.

If you're mixing veg-oil with petroleum diesel or kerosene (exact same as # 1 diesel) you're still using fossilfuel-- cleaner than a lot of, however still not tidy enough, lots of would say. Still, for every single gallon of

grease you utilize, that's one gallon of fossil-fuel saved, and that much less climate-changing carbon in the environment.

People utilize various mixes, 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 perhaps utilize 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 a really hard and tolerant motor-- it won't like it however you most likely won't eliminate it. Otherwise, it's not wise.

To do it properly you'll require 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 requirement for the blends.

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

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

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

They're hard however they'll just take so much abuse. There's no guarantee of it, however utilizing a mix of as much as 20% veg-oil of great quality is stated to be safe enough for older diesels, particularly in summer season.

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

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