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

1. Use the oil just 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 gasoline;

3. Convert it to biodiesel.

The first two approaches sound easiest, but, as so often in life, it's not quite that simple.

1. Mixing it

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

If you're mixing veg-oil with petroleum diesel or kerosene (like # 1 diesel) you're still utilizing fossilfuel-- cleaner than most, however still unclean enough, many would state. Still, for each gallon of

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

People utilize various blends, ranging from 10% vegetable oil and 90% petro-diesel to 90% vegetable oil and 10% petro-diesel. Some individuals just use it that method, start up and go, without pre-heating it (which makes veg-oil much thinner), or perhaps utilize pure grease 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 really tough and tolerant motor-- it won't like it but you most likely will not kill it. Otherwise, it's not smart.

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

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

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

Diesel motor are state-of-the-art makers with very exact fuel requirements, specifically the more modern-day, cleaner-burning diesels (see The TDI-SVO debate).

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

Otherwise using veg-oil fuel needs either a professional SVO service or biodiesel. Mixes and blends are usually a bad compromise. But blends do have an advantage in cold weather condition.

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