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

1. Use the oil just as it is-- generally 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 very first two approaches sound most convenient, however, as so typically in life, it's not quite that easy.

1. Mixing it

Vegetable oil is much more thick (thicker) than either petro-diesel or biodiesel. The function of mixing it or blending it with other fuels is to decrease the viscosity to make it thinner so that it streams more freely through the fuel system into the combustion chamber.

If you're blending veg-oil with petroleum diesel or kerosene (very same as # 1 diesel) you're still utilizing fossilfuel-- cleaner than a lot of, but still unclean enough, many 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 environment.

People use different blends, ranging from 10% vegetable oil and 90% petro-diesel to 90% grease and 10% petro-diesel. Some individuals just utilize it that method, start up and go, without pre-heating it (that makes veg-oil much thinner), or even use 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 an extremely hard and tolerant motor-- it will not like it however you most likely 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, ideally utilizing pure petro-diesel or biodiesel for starts and stops. (See next.) In which case there's no requirement for the blends.

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

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

Diesel motor are state-of-the-art machines with really precise fuel requirements, particularly the more contemporary, cleaner-burning diesels (see The TDI-SVO debate).

They're hard but they'll only take so much abuse. There's no guarantee of it, but using a blend of approximately 20% veg-oil of good quality is said to be safe enough for older diesels, especially in summer.

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

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