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, rho(c) = 0.202 g cm(-3)), 11-nonylheneicosane (T-c = 835 K, rho(c) = 0.208 g cm(-3)), and 2,6,10,15,19,23-hexamethyltetracosane, also called ’squalane’ (T-c = 807 K, rho(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.