Start with some crude oil. Crude oil is petroleum as it comes directly from the well. Crude oil is too heavy and viscous, or thick, to be used as a motor fuel. The heavy crude must be refined, or processed, to yield usable grades of fuel oil. Each of these grades of fuel oil has a unique flash point. The flash point is the temperature at which the fuel ignites. Motor fuel must be appropriate to the engine in which it is used. Each kind of engine burns at its own temperatures and pressures.
Use a process called fractional distillation. The crude oil is placed in a kind of gigantic upright pipe. Small pipes lead off from the main pipe at various points. The main pipe, or distillation column, is a variety of still. Heat the crude oil and you boil the oil. The lighter the fuel oil, the lower its boiling point. The lighter the fuel the higher it rises in the distillation column. Different weights of motor oil are drawn off at each level. Gasoline is a lighter fuel than diesel.
Collect each kind of motor oil in a separate tank. Gasoline is used mostly in cars. The car's internal combustion engine works by exploding the gasoline in a small chamber. Gasoline engines require air to operate. Spark plugs provide the sparks that ignite the mixture of gasoline and air in the combustion chamber. The exploded gas drives a piston that drives your car. The heavier diesel fuel does not require a constant infusion of air.
Use the heavier motor fuel in a diesel engine. Diesel engines operate at higher temperatures and pressures than standard internal combustion engines. A fuel injector sprays the diesel oil into a cylinder. Extremely high pressures cause the fuel to ignite. Normally air is drawn in only at peak compression. The high pressures of the diesel engine mean it can supply enormous amounts of power. This makes them ideal for trucks. Some cars engines also benefit from the direct fuel injection of diesel.
Modify your motor oil to make it suitable for your specific needs. Combustion catalysts can lower the burning temperature. Antiknock agents reduce the knocking and pinging. Knocking an pinging comes from premature explosion of the gasoline. Alcohols like ethanol are often added to reduce the amount of gasoline used. Ethanol and bio-diesels reduce dependence on fossil fuels. They can also help to curb overall pollution.