A grease composition containing: (a) the reaction product of: (i) a calcium containing overbased organic acid; and (ii) at least one acid producing compound or derivatives thereof selected from the group consisting of: (1) a non-polymeric hydrocarbyl substituted dicarbonyl derivative selected from the group consisting of an acid, an ester, a salt, an anhydride, ester-acid, acid-salt and mixtures thereof; (2) a copolymer derived from monomers containing (1) an olefin; and (2) an unsaturated dicarboxylic acid anhydride or derivatives thereof; and (3) an inorganic acid containing about 2 or more acidic hydrogens; and (b) an oil of lubricating viscosity, wherein the overbased calcium sulphonate contains colloidally dispersed calcium carbonate is selected from the group consisting of calcite, vaterite and mixtures thereof. The invention further relates to the process to make the composition and its use in greases to increase water resistance.