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

1. Use the oil just as it is-- typically 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 methods sound most convenient, however, as so frequently in life, it's not quite that easy.

1. Mixing it

Grease is much more viscous (thicker) than either petro-diesel or biodiesel. The function of blending 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 mixing veg-oil with petroleum diesel or kerosene (same as # 1 diesel) you're still using fossilfuel-- cleaner than a lot of, but still not clean enough, many would state. Still, for every single gallon of

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

People utilize various blends, ranging from 10% veggie oil and 90% petro-diesel to 90% grease and 10% petro-diesel. Some individuals simply utilize it that way, launch and go, without pre-heating it (that makes veg-oil much thinner), and 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 a very tough and tolerant motor-- it won't like it however you probably won't eliminate it. Otherwise, it's not smart.

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

Blends with different solvents and/or with unleaded gasoline are "experimental at best", little or absolutely nothing is understood about their results on the combustion qualities of the fuel or their long-term results 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 motor are state-of-the-art machines with really exact fuel requirements, especially the more modern-day, cleaner-burning diesels (see The TDI-SVO debate).

They are difficult however they'll only take so much abuse. There's no assurance of it, however using a blend of as much as 20% veg-oil of great quality is stated to be safe enough for older diesels, especially in summertime.

Otherwise utilizing veg-oil fuel requires either a professional SVO service or biodiesel. Mixes and blends are usually a poor compromise. But mixes do have a benefit in winter.

Just like biodiesel, some kerosene or winterised petro-diesel fuel blended with straight grease decreases the temperature level at which it begins to gel. (See Using biodiesel in winter) More about fuel blending and blends.