Cheapest mineral oil you can find! 20/50 engine oil is fine. No synthetic additives though.
Product Density (kg/L) Energy Content
Light Kerosene 0.79 34.52 MJ/L
Heating oil 0.81 35.20 MJ/L
Diesel (ADF) 0.84 36.18 MJ/L
Ignition Quality or Cetane Number -- This factor influences ease of starting, duration of white smoking after start-up, drivability before warm-up and intensity of diesel knock at idle. Studies have correlated ignition quality with all regulated emissions. As ignition delay is reduced, the combustion process starts earlier and emissions (primarily carbon monoxide and hydrocarbons) are reduced.
Ignition delay is measured by the Cetane Number (CN) test (ASTM D 613), which uses a single-cylinder, variable compression ratio engine analogous to the Octane Number engine. In this case, the ignition delay of the test fuel is measured at a fixed compression ratio. This result is compared with the results from standard reference fuels consisting of blends of n-cetane and heptamethylnonane.
Diesel engines vary widely in their cetane requirements, and there is no commonly recognized way to measure this value. In general, the lower an engine's operating speed, the lower the CN of the fuel it can use. Large marine engines can tolerate fuels with CNs as low as 20, while some manufacturers of high-speed passenger car diesel engines specify 55 CN fuel.
Ordinary pump diesel is - I believe - around 45. Heating oil about 40.
Daz.
