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

1. Use the oil simply as it is-- normally called SVO fuel (straight vegetable 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 techniques sound easiest, but, as so frequently in life, it's not quite that simple.

1. Mixing it

Grease is a lot more thick (thicker) than either petro-diesel or biodiesel. The purpose of blending it or blending it with other fuels is to decrease the viscosity to make it thinner so that it streams more easily through the fuel system into the combustion chamber.

If you're mixing veg-oil with petroleum diesel or kerosene (same as # 1 diesel) you're still using fossilfuel-- cleaner than most, but still not clean enough, lots of would state. Still, for every single gallon of

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

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

To do it properly you'll require what amounts to an SVO system with fuel pre-heating anyhow, 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 various solvents and/or with unleaded gas are "speculative at best", little or nothing is understood about their impacts on the combustion qualities of the fuel or their long-term effects on the engine.

Higher viscosity is not the only issue with using grease as fuel. Veg-oil has different chemical homes and combustion qualities from the petroleum diesel fuel for which diesel engines and their fuel systems are developed.

Diesel engines are state-of-the-art devices with really exact fuel requirements, particularly the more modern, cleaner-burning diesels (see The TDI-SVO debate).

They're difficult however they'll just take so much abuse. There's no assurance of it, but utilizing a mix of approximately 20% veg-oil of excellent quality is said to be safe enough for older diesels, especially in summer season.

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

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