There are at least 3 methods to run a diesel motor on biofuel utilizing vegetable oils, animal fats or both. All 3 are used with both fresh and pre-owned 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 blend it with a solvent, or with gasoline;

3. Convert it to biodiesel.

The very first two approaches sound simplest, however, as so typically in life, it's not rather that basic.

1. Mixing it

Grease is far more viscous (thicker) than either petro-diesel or biodiesel. The purpose of blending it or blending it with other fuels is to reduce 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 using fossilfuel-- cleaner than most, but still unclean enough, many would say. Still, for every single gallon of

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

People use different blends, varying from 10% vegetable oil and 90% petro-diesel to 90% grease and 10% petro-diesel. Some individuals simply utilize it that method, start up and go, without pre-heating it (that makes veg-oil much thinner), or even use 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 an extremely difficult and tolerant motor-- it will not like it however you probably won't kill it. Otherwise, it's not smart.

To do it effectively you'll require 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 mixes.

Blends with different solvents and/or with unleaded fuel are "experimental at best", little or absolutely nothing is known about their results on the combustion characteristics of the fuel or their long-lasting results on the engine.

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

Diesel engines are state-of-the-art makers with very precise fuel requirements, particularly the more contemporary, cleaner-burning diesels (see The TDI-SVO debate).

They are difficult but they'll only take a lot abuse. There's no guarantee of it, however using a blend of as much as 20% veg-oil of good quality is said to be safe enough for older diesels, especially in summer.

Otherwise utilizing veg-oil fuel requires either an expert SVO solution or biodiesel. Mixes and blends are normally a bad compromise. But mixes do have an advantage in cold weather.

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