There are at least 3 methods to run a diesel engine on biofuel utilizing vegetable oils, animal fats or both. All three are used with both fresh and pre-owned oils.

1. Use the oil simply as it is-- normally called SVO fuel (straight veggie 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 two methods sound easiest, but, as so typically in life, it's not rather that basic.

1. Mixing it

Grease is far more thick (thicker) than either petro-diesel or biodiesel. The purpose of mixing it or blending it with other fuels is to reduce the viscosity to make it thinner so that it streams more easily 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 using fossilfuel-- cleaner than a lot of, but still not clean enough, numerous would say. Still, for each gallon of

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

People utilize different blends, ranging from 10% grease and 90% petro-diesel to 90% grease and 10% petro-diesel. Some people simply use it that way, start up and go, without pre-heating it (that makes veg-oil much thinner), or perhaps use pure vegetable oil 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 very tough and tolerant motor-- it will not like it but 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, ideally utilizing pure petro-diesel or biodiesel for starts and stops. (See next.) In which case there's no requirement for the mixes.

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

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

Diesel engines are modern devices with very exact fuel requirements, specifically the more modern-day, 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 blend of as much as 20% veg-oil of great quality is stated to be safe enough for older diesels, especially in summer.

Otherwise utilizing 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 mixed with straight grease decreases the temperature level at which it begins to gel. (See Using biodiesel in winter season) More about fuel mixing and blends.