Results of analysis of the spectral characteristics of promising liquid carriers with different viscosities and natures at room temperature in the terahertz spectral range are given. The spectral absorption characteristics of the examined liquid layers with thickness of 3, 6, and 9 mm in the range from 0.3 to 2 THz are presented. It is shown that synthetic Toyota motor oil 5w40 is promising as a liquid carrier for synthesis and application of a magnetic liquid for the THz range regardless of the thickness of the layer of the examined sample.