cetane is like octane in a gas engine.
not really, octane in gas is resistance to knock
cetane, you want it to have better properties to ignite under compression.
Higher cetane is better until a certain point of diminishing returns.
Shell has SunDiesel which is biomass-to-liquid fuel, which is approved by the diesel manufacturers in Europe, as it does not gum up critical diesel injection components, like a traditional FAME biodisel