Abstract: Liquid fuels such as a diesel engine fuel mixture or a light heating oil have as a main component, a fossil diesel engine fuel and/or a biodiesel and/or a vegetable oil and additives. The object is to provide an alternative mixture component for diesel engine fuels or light heating oil which is suitable not only for fossil diesel engine fuels but also biodiesel or vegetable oil, which may be produced inexpensively and which meets the requirements as a pure bio propellant. It is proposed that diesel engine fuel mixture or light heating oil contains, as a mixture component, diethyl oxalate. The heating oil can be made of a mixture which originates from the refining of crude oil and is admixed with up to 25% by volume diethyl oxalate. In addition, for the heating oil, use can be made of a mixture which consists of vegetable oils and up to 50% by volume diethyl oxalate.