There are at least 3 ways to run a diesel motor on biofuel using veggie oils, animal fats or both. All 3 are used with both fresh and pre-owned 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 mix it with a solvent, or with fuel;

3. Convert it to biodiesel.

The very first 2 approaches sound easiest, however, as so often in life, it's not rather that easy.

1. Mixing it

Grease is much more thick (thicker) than either or biodiesel. The purpose of blending it or mixing it with other fuels is to lower 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 (exact same as # 1 diesel) you're still using fossilfuel-- cleaner than a lot of, but still unclean enough, numerous would state. Still, for every gallon of

vegetable oil you utilize, that's one gallon of fossil-fuel conserved, and that much less climate-changing carbon in the atmosphere.

People utilize numerous blends, varying from 10% veggie oil and 90% petro-diesel to 90% vegetable oil and 10% petro-diesel. Some people just utilize it that method, launch 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 might get away with it with an older Mercedes 5-cylinder IDI diesel, which is a very tough and tolerant motor-- it won't like it but you probably will not eliminate it. Otherwise, it's not wise.

To do it correctly you'll need what totals up 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 requirement for the mixes.

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

Higher viscosity is not the only problem with using grease as fuel. Veg-oil has various chemical homes and combustion characteristics from the petroleum diesel fuel for which diesel motor and their fuel systems are designed.

Diesel engines are high-tech devices with really precise fuel requirements, specifically the more modern-day, cleaner-burning diesels (see The TDI-SVO debate).

They're hard but they'll just take so much abuse. There's no assurance of it, however 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 needs either a professional SVO option or biodiesel. Mixes and blends are generally a bad compromise. But mixes do have a benefit in cold weather condition.

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