Mass of Substance = Volume of Substance x Density of Substance
Density of petrol, natural = 711.22 kg/m3
Density of petrol, natural in tonne/litre = 1.5679698363999999
Mass of a Substance = 1.5679698363999999 x 8
8 litre of petrol, natural weighs 12.543758691199999 tonne