Siloxane mixtures

The invention provides mixtures, liquid at 25 DEG C, of methylpolysiloxanes comprising at least two methylpolysiloxanes selected from linear compounds of the general formula I Me3SiO-(Me2SiO)x-SiMe3 (I), and cyclic compounds of the general formula II (Me2SiO)y (II), wherein the mixture comprises at least one linear methylpolysiloxane of the general formula I and at least one cyclic methylpolysiloxane of the general formula II, Me means methyl radical, x has values greater than or equal to zero and the arithmetic mean of x, weighted by the molar proportions, over all linear methylpolysiloxanes is between 3 and 20, y has values greater than or equal to 3 and the arithmetic mean of y, weighted by the molar proportions, over all cyclic methylpolysiloxanes is between 3 and 6, the numerical ratio of the Me3Si- chain ends groups in the compounds of the general formula I to the sum of the Me2SiO- units in the compounds of the general formulae I and II is at least 1:2 and at most 1:10, and further definitions are described in claim 1, and the use of the mixtures as heat carrier fluids.