Dew points have been measured for binary propane or n-butane + carbon dioxide mixtures at pressures from 1.2 x 10(5) to 34.9 x 10(5) Pa and temperatures from 192.6 to 274.8 K, four ternary propane or n-butane + carbon dioxide + water mixtures from 1.1 x 10(5) to 20.7 x 10(5) Pa and temperatures from 247.5 to 289.0 K, and eight quaternary propane or n-butane + carbon dioxide + water + methanol mixtures from 1.1 x 10(5) to 21.8 x 10(5) Pa and temperatures from 249.8 to 289.9 K. The results are analyzed in terms of a predictive EF-EOS excess-function equation of state method based on the zeroth-approximation of Guggenheim's reticular model. This method has been chosen because it can be used to adequately predict the dew points of all the mixtures of our interest in the dew temperature and pressure ranges. In fact, the model reproduces the experimental dew-point temperature data within an AAD ( absolute average deviation) of 1.6 and 1.3 K for the binary systems, between 0.1 and 2.5 K for the ternary systems, and between 0.0 and 5.1 K for the quaternary systems. The experimental results obtained for ternary propane or n-butane + carbon dioxide + water mixtures at pressure values higher than 5 x 10(5) Pa were also compared to a predictive EOS ( equation of state) model. It reproduced experimental dew-point temperature data within AAD between 0.0 and 5.5 K.