The present invention relates to a mixture of polyalkylsiloxanes obtainable through a hydrosilylation reaction wherein a mixture of monounsaturated olefins is reacted with an amount of one or more polyalkylhydrosiloxanes in the presence of a hydrosilylation catalyst. Furthermore, the invention concerns polyalkylsiloxane comprising alkyl side chains consisting of linear or branched alkyl groups with 40 to 60 carbon atoms, with 16 to 30 carbon atoms, and 6 to 15 carbon atoms. In addition, the present invention relates to water-based compositions suitable for use in metal casting processes as a mold release agent comprising a mixture of polyalkylsiloxanes, a non-ionic surfactant having a HLB value of at least 8, and less than 20 wt.-% of waxes. In addition, the present invention relates to the use of the polyalkylsiloxanes and mixtures of polyalkylsiloxanes.