A product suitable for use as an additive for lubricating oils is obtained by reacting an oxide of lead with a guanidine or substituted guanidine salt of a phosphosulphurized hydrocarbon at a temperature not less than 250 DEG F. and below the decomposition temperature of the reaction product. The reaction may be conducted in the presence of water or steam but is preferably effected under substantially anhydrous conditions. Generally enough lead oxide is used to form a product containing from 1 to 25 per cent or higher ash content after ignition. The lead oxide may be PbO, Pb3O4, Pb2O3 or PbO2 and the reaction mixture is preferably blown with an inert gas such as nitrogen during the reaction and the product filtered, e.g. through diatomaceous earth to remove insoluble materials. The phosphosulphurized hydrocarbon may be prepared by reacting a hydrocarbon with a sulphide of phosphorus, e.g. P2S3, P2S5, P4S3 and P4S7 generally at 200-600 DEG F., the reaction being preferably carried out in a non-oxidizing atmosphere such as nitrogen and if desired the reaction product may be further treated by blowing with steam, alcohol or ammonia at 200-600 DEG F. Specified hydrocarbons include mono-olefin polymers having molecular weight ranges from about 100 to 50,000 and obtained by the polymerization of low molecular weight olefins such as ethylene and isobutylene. The substituted guanidine may be biguanide, dicyandiamide or dicyandiamidine or a hydrocarbon substituted guanidine, e.g. guanidine substituted by straight and branched chain alkyl groups or cycloalkyl or alkyl, aryl or alkaryl groups. The guanidine or substituted guanidine salt of the phosphosulphurized hydrocarbon may be prepared by the procedures disclosed in Specification 684,168 and preferably by reacting the phosphosulphurized hydrocarbon with the guanidino compound in a non-oxidizing atmosphere at about 100 DEG to 400 DEG F., if desired in the presence of a solvent such as naphtha. The guanidino compound may be used in the form of a carbonate, thus guanidine carbonate may be dissolved in water and then reacted with the phosphosulphurized hydrocarbon. The lubricating oil base stocks may be straight mineral lubricating oils or distillates derived from paraffinic, naphthenic or mixed base crudes or may be synthetic oils such as the dibasic acid esters or glycol ethers or may be mixtures of such synthetic oils and mineral oils. The products may be used in conjunction with other types of additives, e.g. pour point depressors, sludge dispersers, antioxidants, viscosity index improvers and oiliness agents and may also be used in hydraulic fluids, cutting oils and turbine oils.ALSO:A product suitable for use as an additive for lubricating oils (see Group III) is obtained by reacting an oxide of lead with a guanidine or substituted guanidine salt of a phospho-sulphurized hydrocarbon at a temperature not less than 250 DEG F. and below the decomposition temperature of the reaction product. The oxide of lead may be PbO, Pb3O4, Pb2O3 or PbO2 and the reaction may be conducted in the presence of water or steam but is preferably carried out under substantially anhydrous conditions. Generally, enough lead oxide is used to form a reaction product containing from 1 to 25 per cent or higher ash content after ignition and the reaction mixture is preferably blown with an inert gas such as nitrogen during the reaction step and the product filtered e.g. through a diatomaceous earth to remove insoluble materials. The phospho-sulphurized hydrocarbon may be prepared by reacting a hydrocarbon with a sulphide of phosphorus such as P2S3, P2S5, P4S3 or P4S7, generally at 200-600 DEG F., using from 1 to 10 and preferably 2 to 5 mols. of hydrocarbon per mol. of the phosphorus sulphide and the reaction is preferably carried out in a non-oxidizing atmosphere such as nitrogen. If desired the reaction product may be further treated by blowing with steam, alcohol, or ammonia, at 200-600 DEG F. Specified hydrocarbons include olefins, olefin polymers (see Group IV (a)), diolefins, acetylenes, aromatics, alkyl aromatics, alicyclics, petroleum fractions such as lubricating oil distillates, petrolatums, cracked cycle stocks, condensation products of petroleum fractions, and solvent extracts of petroleum fractions. Specified monolefines are isobutylene, decene, cerotene, olefinic extracts from gasoline, and cracked waxes. Other hydrocarbons which may be used include aromatic hydrocarbons such as benzene, naphthalene, anthracene, xylenes, aralkyl and alkaryl hydrocarbons, and condensation products of halogenated aliphatic hydrocarbons with an aromatic compound in the presence of a Friedel-Crafts' type catalyst. The guanidine or substituted guanidine derivative of the phosphosulphurized hydrocarbon may be obtained by the procedures disclosed in Specification 684,168. Several hydrocarbon-substituted guanidines are specified including those substituted by straight and branched chain alkyl groups, and cycloalkyl, aralkyl, aryl or alkaryl groups. The preferred substituted guanidines are the symmetrical trialkyl, trinaphthenyl and triaralkyl guanidines, and the monoalkyl, mononaphthenyl, monoaralkyl and unsymmetrical dialkyl, dinaphthenyl and diaralkyl guanidines. Other substituted guanidines may be used such as biguanide, dicyandiamide and dicyandiamidine. The guanidine or substituted guanidine salt of the phospho-sulphurized hydrocarbon is preferably prepared by reacting the latter with the guanidine compound, in a non-oxidizing atmosphere, at about 100 DEG to 400 DEG F., if desired in the presence of a solvent such as naphtha. The guanidino compound may be used in the form of a carbonate, thus guanidine carbonate may be dissolved in water and then reacted with the phosphosulphurized hydrocarbon. In examples, a product is obtained by racting a phenol-extracted Bright Stock with phosphorus pentasulphide at 430-460 DEG F. in an atmosphere of nitrogen and in the presence of a silicone polymer which is added to prevent foaming. The product is filtered through a diatomaceous earth and then reacted with an aqueous solution of guanidine carbonate at 300-330 DEG F. in an atmosphere of nitrogen to yield the guanidine salt. The latter is then reacted at 380 DEG to 400 DEG F. with PbO and with Pb3O4 respectively, the reactants in the latter case being blown with nitrogen during the reaction period. The product is filtered in each case before use as a lubricant additive. A comparative example is also given in which the acidic phosphorus pentasulphide treated Bright Stock is reacted directly with PbO at 380 DEG to 400 DEG F. but no appreciable reaction takes place in this case.ALSO:A lubricating oil composition comprises a major proportion of a lubricating oil and a minor proportion of the product obtained by reacting an oxide of lead with a guanidine or hydrocarbon-substituted guanidine salt of a phosphosulphurized hydrocarbon at a temperature not less than 250 DEG F. and below the decomposition temperature of the reaction product. The reaction may be conducted in the presence of water or steam but is preferably carried out under substantially anhydrous conditions. The oxide of lead may be PbO, Pb3O4, Pb2O3 or PbO2 and generally enough lead oxide is used to form a product containing from 1 to 25 per cent or higher ash content after ignition. The reaction mixture is preferably blown with an inert gas such as nitrogen during the reaction and the product is preferably filtered, e.g. through a diatomaceous earth, to remove insoluble materials. The phosphosulphurized hydrocarbon may be obtained by reacting a phosphorus sulphide such as P2S3, P2S5, P4S3 and P4S7 with the hydrocarbon preferably in a non-oxidizing atmosphere such as nitrogen and the reaction product may be further treated by blowing with steam, alcohol, or ammonia, at 200-600 DEG F. Specified hydrocarbons include olefins, olefin polymers (see Group IV (a)), diolefins, acetylenes, aromatics, alkyl aromatics, alicyclics, petroleum fractions such as lubricating oil distillates, petrolatums, cracked cycle stocks, condensation products of petroleum fractions, and solvent extracts of petroleum fractions. The guanidine derivative may be a hydrocarbon substituted guanidine or it may be biguanide, dicyandiamide or dicyandiamidine. Several hydrocarbon substituted guanidines are specified including those substituted by straight and branched chain alkyl groups, or cycloalkyl aralkyl, aryl or alkaryl groups. The guanidine or substituted guanidine salt of the phosphosulphurized hydrocarbon may be prepared by the procedures disclosed in Specification 684,168 and preferably by reacting the phosphosulphurized hydrocarbon with the guanidino compound in a non-oxidizing atmosphere at about 100 DEG to 400 DEG F., if desired in the presence of a solvent such as naphtha. The guanidino compound may be used in the form of a carbonate, thus guanidine carbonate may be dissolved in water and then reacted with the phosphosulphurized hydrocarbon. The lubricating oil base stocks may be straight mineral lubricating oils or distillates derived from paraffinic naphthenic or mixed base crudes or may be synthetic oils such as the dibasic acid esters or glycol ethers, or may be mixtures of such synthetic oils and mineral oils. The products may be used in conjunction with other types of additives, e.g. pour point depressors, sludge dispersers, antioxidants, viscosity index improvers and oiliness agents and may also be used in hydraulic fluids, cutting oils, and turbine oils. Examples are given to show the properties as an additive to an aviation oil of the product obtained by reacting the guanidine salt of a phosphosulphurized phenol-extracted Bright Stock (see Group IV (b)) with PbO and Pb3O4 respectively at 380 DEG to 400 DEG F., the reaction with Pb3O4 being carried out