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

1. Use the oil just as it is-- normally 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 gasoline;

3. Convert it to biodiesel.

The first two methods sound easiest, but, as so typically in life, it's not quite that simple.

1. Mixing it

Grease is far more thick (thicker) than either petro-diesel or biodiesel. The function of mixing it or blending 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 mixing veg-oil with petroleum diesel or kerosene (very same as # 1 diesel) you're still using fossilfuel-- cleaner than many, but still not tidy enough, lots of would state. Still, for every gallon of

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

People use different blends, varying from 10% grease and 90% petro-diesel to 90% vegetable oil and 10% petro-diesel. Some individuals just use it that way, launch and go, without pre-heating it (which makes veg-oil much thinner), or even use 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 really tough and tolerant motor-- it won't like it however you probably will not kill it. Otherwise, it's not smart.

To do it properly you'll need 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 mixes.

Blends with different solvents and/or with unleaded gasoline are "speculative at best", little or absolutely nothing is understood about their results on the combustion attributes of the fuel or their long-term effects on the engine.

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

Diesel motor are modern machines with extremely exact fuel requirements, specifically the more modern-day, cleaner-burning diesels (see The TDI-SVO controversy).

They're difficult however they'll just take so much abuse. There's no guarantee of it, however utilizing a blend of up to 20% veg-oil of great quality is stated to be safe enough for older diesels, particularly in summer season.

Otherwise using veg-oil fuel requires either an expert SVO service or biodiesel. Mixes and blends are usually a poor compromise. But mixes do have an advantage in cold weather.

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