Abstract: A process for making an overbased low-soap alkaline earth metal hydrocarbylsulfonate in a single stage by mixing in an inert diluent (a) a hydrocarbyl sulfonic acid of 400-1500 molecular weight, (b) alkaline earth metal oxide or hydroxide in an amount to provide a stoichiometric excess equivalent to a total base number of at least 200 and to provide a "metal ratio" of at least 0.02.times.mol wt of the sulfonic acid, (c) an alkanol of 1-4 carbon atoms, preferably methanol, (d) water and (e) ammonium formate and then passing carbon dioxide into the mixture to convert excess alkaline earth metal base to carbonate.