Bubble point pressures and densities were measured with a variable volume cell for the binary systems propane + triacontane (n-C30H62), + hexatriacontane (n-C36H74), + tetracontane (n-C40H82), + pentacontane (n-C50H102), and + squalane (C30H62,2,6,10,15,19,23-hexamethyltetracosane). The densities were measured for compressed liquids or supercritical fluids in the one-phase region. The studied temperature and pressure ranges were 353-373 K and 4.00-7.00 MPa, respectively. The mass fractions of the long-chain alkanes varied between 0 and 0.0326. It was found that the densities of the mixtures increased almost linearly with the mass fractions of the heavy alkanes. The effects of all the long-chain alkanes on the density did not depend on molar mass. Bubble point pressures decreased only very slightly as the mass fractions of the long-chain alkanes increased.