There are at least three ways to run a diesel motor on biofuel utilizing veggie oils, animal fats or both. All 3 are utilized with both fresh and secondhand oils.

1. Use the oil simply as it is-- usually 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 gasoline;

3. Convert it to biodiesel.

The first two approaches sound most convenient, however, as so frequently in life, it's not rather that simple.

1. Mixing it

Vegetable oil is much more thick (thicker) than either petro-diesel or biodiesel. The function of blending it or blending it with other fuels is to decrease the viscosity to make it thinner so that it flows more easily 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 the majority of, however still unclean enough, lots of would say. Still, for each gallon of

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

People use numerous blends, varying from 10% grease and 90% petro-diesel to 90% grease and 10% petro-diesel. Some individuals simply use it that way, launch and go, without pre-heating it (which makes veg-oil much thinner), and even utilize pure vegetable 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 hard and tolerant motor-- it will not like it however you probably won't kill it. Otherwise, it's not sensible.

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

Blends with different solvents and/or with unleaded fuel are "experimental at finest", little or absolutely nothing is understood about their impacts on the combustion characteristics of the fuel or their long-term impacts on the engine.

Higher viscosity is not the only problem with using vegetable oil as fuel. Veg-oil has different chemical properties and combustion attributes from the petroleum diesel fuel for which diesel motor and their fuel systems are designed.

Diesel engines are modern machines with very exact fuel requirements, specifically the more modern, cleaner-burning diesels (see The TDI-SVO debate).

They're tough but they'll just take a lot abuse. There's no assurance of it, however using a mix of as much as 20% veg-oil of good quality is stated to be safe enough for older diesels, especially in summer.

Otherwise using veg-oil fuel requires either an expert SVO service or biodiesel. Mixes and blends are usually a bad compromise. But blends do have a benefit in winter.

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