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

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

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

3. Convert it to biodiesel.

The first 2 methods sound simplest, however, as so often in life, it's not rather that easy.

1. Mixing it

Grease is much more viscous (thicker) than either petro-diesel or biodiesel. The purpose of mixing it or blending it with other fuels is to lower the viscosity to make it thinner so that it streams more easily 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, numerous would say. Still, for each gallon of

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

People use numerous blends, ranging from 10% veggie oil and 90% petro-diesel to 90% vegetable oil and 10% petro-diesel. Some people just use it that way, launch and go, without pre-heating it (that makes veg-oil much thinner), or even 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 tough and tolerant motor-- it won't like it however you most likely won't kill it. Otherwise, it's not wise.

To do it correctly you'll require what amounts to an SVO system with fuel pre-heating anyhow, preferably using 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 "experimental at best", little or nothing is learnt about their results on the combustion attributes of the fuel or their long-term impacts on the engine.

Higher viscosity is not the only issue with utilizing grease as fuel. Veg-oil has different chemical residential or commercial properties and combustion characteristics from the petroleum diesel fuel for which diesel engines and their fuel systems are designed.

Diesel motor are state-of-the-art makers with really exact fuel requirements, especially the more contemporary, 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 approximately 20% veg-oil of great 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 normally a poor compromise. But blends do have a benefit in cold weather condition.

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