Diesel engine oil, also known as diesel fuel, is refined from crude oil and biomass materials and is used with diesel engines. What makes diesel engine oils so unique is that they have a high anti-wear load in Zinc form. Therefore, the catalytic converter in diesel oils can fight off corrosion and rust, online gasoline. They have a higher viscosity level, and each oil has a proprietary blend of additives that enhances its performance. As for how it works, the oil is pumped through the engine under high pressure that lubricates the internal components and separates metal parts.