In this work, we present improved estimates of the critical temperature (T-c), critical density (rho(c)), critical pressure (P-c), and critical compressibility factor (Z(c)) for n-alkanes with chain lengths as large as C-48. These are obtained for several different force field models with Gibbs ensemble Monte Carlo simulations. We implement a recently proposed data analysis method designed to reduce the uncertainty in T-c, rho(c), P-c, and Z(c) when predicted with molecular simulation. The results show a large reduction in the uncertainties compared to the simulation literature with the greatest reduction found for rho(c), P-c, and Z(c). Previously, even the most computationally intensive molecular simulation studies have not been able to elucidate the n-alkane P-c trend with respect to larger carbon numbers. The results of this study are significant because the uncertainty in P-c is small enough to discern between conflicting experimental data sets and prediction models for large n-alkanes. Furthermore, the results for T-c resolve a discrepancy in the simulation literature with respect to the correct T-c trend for large n-alkanes. In addition, the Z(c) results are reliable enough to determine the most accurate prediction trend for Z(c). Finally, finite-size effects are shown to not be significant even for the relatively small system sizes required for efficient simulation of longer chain lengths.