Direct configurational-bias Monte Carlo simulations in the Gibbs ensemble have been used to determine the vapor-liquid coexistence curves and critical points of three C₃₀H₆₂ isomers: n-triacontane (T_c = 851 K, p_c = 0.202 g cm⁻³), 11-nonylheneicosane (T_c = 835 K, p_c = 0.208 g cm⁻³), and 2,6,10,15,19,23-hexamethyl-tetracosane, also called ‘squalane’ (T_c = 807 K, p_c = 0.244 g cm⁻³). The calculations show that the molecular shape can have a substantial influence on the phase diagrams of isomeric alkanes and that, in particular, squalane deviates significantly from the principle of corresponding states.