Oil soluble sulphonates are prepared by sulphonating a hydrocarbon oil containing hydrocarbon sulphonatable at below 35 DEG C. to yield oil soluble sulphonates, with not more than 15% by weight of the weakest sulphonating agent selected from 66 DEG Baum<\>ae sulphuric acid, 98-100% sulphuric acid, an oleum, chlorosulphonic acid, fluoro sulphonic acid and SO3, able to sulphonate some of the hydrocarbon at below 35 DEG C., the sulphonation being affected at below 35 DEG C. while maintaining the reactants in intimate admixture and allowing a contact time sufficient only for mono-sulphonation to occur, thereafter neutralizing the resulting sulphonic acids before any secondary reactions occur, treating the sulphonated oil, separated or not from an acid fraction containing sulphonic acids in excess acid reagent, before, during or after the neutralization step with an alcohol having less than 4 carbon atoms in the presence of sufficient water to form at least an oil phase and a hydro-alcoholic phase containing dissolved sulphonated hydrocarbons, separating and if necessary neutralizing the hydro-alcoholic phase, then adding to the separated neutralized alcoholic solution sufficient of the said alcohol containing at most 10% by weight of water to form three phases: oil, an alcoholic solution of the sulphonates and an aqueous solution of metal salts, then recovering the oil, separating the sulphonate phase and distilling it to recover the solvent, removing any last residue of precipitated inorganic salts and obtaining purified sulphonates containing minor proportions of oil. The recovered oil may be repeatedly treated by the above series of steps using the appropriate sulphonating agent able to react with the sulphonatable hydrocarbon remaining in the oil. The hydrocarbon oils treated may be petroleum oils which may be solvent extracted, shale oil, coal oils and synthetic oils. In one embodiment, the sulphonation product is separated into an oil solution of sulphonic acids and an acid phase comprising sulphonic acids in excess sulphonating agent. The oil solution is then either neutralized, separated from an aqueous salt phase, and mixed with a 50:50 water-ethanol or -isopropanol mixture or the oil solution is mixed with the alcohol containing not more than 10% water during or after neutralization before any separation of metal salts; in each case three phases: oil, hydroalcoholic solution of sulphonates and aqueous salt solution are formed and separated and the sulphonate phase is mixed with alcohol containing not more than 10% water whereby the three phases are again formed and separated and the alcoholic phase is distilled to obtain the sulphonates. The aforesaid acid phase of sulphonic acids and excess acid reagent may be worked up in the same manner to recover oil and sulphonates, or be neutralized, separated from aqueous salts and then extracted with 90% alcohol to recover the sulphonates. In another embodiment, the whole sulphonation mixture is worked up by either of these methods. A further embodiment comprises treating the acid sulphonation mixture with the 50:50 aqueous alcohol to form three phases of oil, hydroalcoholic solution of sulphonic acids and a layer of excess acid reagent, separating and neutralizing the alcoholic phase and extracting the sulphonates therefrom with alcohol as above. The sulphonation mixture may be clarified, before further treatment, by means of powdered aluminium or sodium aluminate or an absorptive earth. The neutralization may be effected with sodium hydroxide or carbonate, ammonia, lime wash or aqueous baryta. The 50:50 aqueous alcohol extractant may include an alkanolamine or soap thereof to improve phase separation. Ammonium sulphonates obtained according to the process may be converted into lithium, calcium, aluminium, molybdenum or other sulphonates by reaction with bases or salts. Examples describe inter alia (1) the repeated sulphonation with oleum, with intermediate neutralization and alcoholic extraction of the sulphonates, of a solvent extracted sulphuric acid washed Coastal oil to give a variety of oil soluble sulphonates and purified oil; (5) the repeated sulphonation of a spindle oil with 66 DEG Baum<\>ae sulphuric acid, 98-100% sulphuric acid and oleum with neutralization and recovery of sulphonates after each sulphonation yielding white oil and oil soluble sulphonates; when oleum only is used in the sulphonation it is stated that large amounts of water soluble sulphonates are also formed; and (7) the sulphonation of a high boiling fraction obtained in the alkylation of benzene and comprising fully alkylated hydrocarbons and sulphonable hydrocarbons. Specification 823,237 is referred to.ALSO:Refined hydrocarbon oils are prepared by sulphonating a hydrocarbon oil containing hydrocarbon sulphonatable at below 35 DEG C. to yield oil-soluble sulphonates, with not more than 15% by weight of the weakest sulphonating agent selected from 66 DEG Baume<\>ae sulphuric acid, 98-100% sulphuric acid, an oleum, chlorosulphonic acid, fluoro sulphonic acid and SO3, able to sulphonate some of the hydrocarbon at below 35 DEG C., the sulphonation being effected at below 35 DEG C. while maintaining the reactants in intimate admixture and allowing a contact time sufficient ohly for mono-sulphonation to occur, thereafter neutralizing the resulting sulphonic acids before any secondary reactions occur, treating the sulphonated oil, separated or not from an acid fraction containing sulphonic acids in excess acid reagent, before, during or after the neutralization step with an alcohol having less than 4 carbon atoms in the presence of sufficient water to form at least an oil phase and a hydro-alcoholic phase containing dissolved sulphonated hydrocarbons, separating and if necessary neutralizing the hydro-alcoholic phase, then adding to the separated neutralized alcoholic solution sufficient of the said alcohol containing at most 10% by weight of water to form three phases: oil, an alcoholic solution of the sulphonates and an aqueous solution of metal salts, then recovering the oil, separating the sulphonate phase and distilling it to recover the solvent, removing any last residue of precipitated inorganic salts and obtaining purified sulphonates containing a minor proportion of oil. The recovered oil may be repeatedly refined by the above series of steps using the appropriate sulphonating agent able to react with the sulphonatable hydrocarbon remaining in the oil. The hydrocarbon oils treated may be petroleum oils which may be solvent extracted, shale oil, coal oils and synthetic oils. In one embodiment, the sulphonation product is separated into an oil solution of sulphonic acids and an acid phase comprising sulphonic acids in excess sulphonating agent. The oil solution is then either neutralized, separated from an aqueous salt phase, and mixed with a 50 : 50 waterethanol or isopropanol mixture or the oil solution is mixed with the alcohol containing not more than 10% water during or after neutralization before any separation of metal salts; in each case three phases: oil, hydro-alcoholic solution of sulphonates and aqueous salt solution are formed and separated and the sulphonate phase is mixed with alcohol containing not more than 10% water whereby the three phases are again formed and separated and the alcoholic phase is distilled to obtain the sulphonates. The aforesaid acid phase of sulphonic acids and excess acid reagent may be worked up in the same manner to recover oil and sulphonates therefrom. In another embodiment, the whole sulphonation mixture is worked up by either of these methods. A further embodiment comprises treating the acid sulphonation mixture with the 50 : 50 aqueous alcohol to form three phases of oil, hydro-alcoholic solution of sulphonic acids and a layer of excess acid reagent, separating and neutralizing the alcoholic phase and extracting the sulphonates therefrom with alcohol as above. The sulphonation mixture may be clarified, before further treatment, by means of powdered aluminium or sodium aluminate or an absorptive earth. The neutralization may be effected with sodium hydroxide or carbonate, ammonia, lime wash or aqueous baryta. The 50 : 50 aqueous alcohol extractant may include an alkanolamine or soap thereof to improve phase separation. Ammonium sulphates obtained according to the process may be converted into lithium, calcium, aluminium, molybdenum or other sulphonates by reaction with bases or salts. Examples describe inter alia (1) the repeated sulphonation with oleum, with intermediate neutralization and alcoholic extraction of the sulphonates, of a solvent extracted sulphuric acid washed Coastal oil to give a variety of oil soluble sulphonate and purified oil; (5) the repeated sulphonation of a spindle oil with 66 DEG Baume<\>ae sulphuric acid, 98-100% sulphuric acid and oleum with neutralization and recovery of sulphonates after each sulphonation yielding white oil and oil soluble sulphonates; when oleum only is used in the sulphonation it is stated that large amounts of water soluble sulphonates are also formed; and (7) the treatment of a high boiling fraction obtained in the alkylation of benzene and comprising fully alkylated hydrocarbons and sulphonatable hydrocarbons. Specification 823,237 is referred to.