There are at least 3 methods to run a diesel engine on biofuel utilizing vegetable oils, animal fats or both. All 3 are utilized with both fresh and pre-owned oils.

1. Use the oil simply as it is-- usually called SVO fuel (straight veggie oil);

2. Mix it with kerosene (paraffin) or petroleum diesel fuel, or with biodiesel, or mix it with a solvent, or with gas;

3. Convert it to biodiesel.

The very first two methods sound simplest, but, as so frequently in life, it's not quite that simple.

1. Mixing it

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

If you're blending veg-oil with petroleum diesel or kerosene (exact same as # 1 diesel) you're still using fossilfuel-- cleaner than most, but still unclean enough, many would state. Still, for every gallon of

veggie oil you use, that's one gallon of fossil-fuel saved, and that much less climate-changing carbon in the atmosphere.

People use numerous blends, ranging from 10% grease and 90% petro-diesel to 90% veggie oil and 10% petro-diesel. Some people simply utilize it that method, launch and go, without pre-heating it (that makes veg-oil much thinner), or even 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 an extremely difficult and it won't like it however you probably won't kill it. Otherwise, it's not smart.

To do it correctly you'll need what totals up 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 blends.

Blends with various solvents and/or with unleaded gasoline are "experimental at best", little or absolutely nothing is learnt about their effects on the combustion attributes of the fuel or their long-term impacts on the engine.

Higher viscosity is not the only issue with utilizing grease as fuel. Veg-oil has various chemical residential or commercial properties and combustion qualities from the petroleum diesel fuel for which diesel engines and their fuel systems are created.

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

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

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

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