One of the main drawbacks in the analysis of the dynamics of the solar core comes from the lack of consistent data sets that cover the low and intermediate degree range (ell = 1,200). It is usually necessary to merge data obtained from different instruments and/or fitting methodologies and hence one introduces undesired systematic errors. In contrast, we present the results of analyzing MDI rotational splittings derived by a single fitting methodology applied to 4608-, 2304-, etc..., down to 182-day long time series. The direct comparison of these data sets and the analysis of the numerical inversion results have allowed us to constrain the dynamics of the solar core and to establish the accuracy of these data as a function of the length of the time-series.