PURPOSE: To obtain a rust preventive wax, having excellent rust preventive, permeability, drying and film removing properties as well as heat and water resistance and useful for automobiles, by blending a wax oxidation product with microcrystalline wax, organic amine, water-soluble resin and water, etc.

CONSTITUTION: An emulsion type rust preventive wax, consisting of (A) 10W40wt.% wax oxidation product, prepared by oxidizing petroleum wax with a blend gas of air with oxygen gas at 1:0.0005W0.1 volume ratio of the oxygen gas to the air at 100W200°C temperature and having 10W60mgKOH/g acid value with (B) 5W20wt.% microcrystalline wax, (C) 1W5wt.% organic amine, e.g. hexylamine, etc., (D) 5W15wt.% water-soluble resin, e.g. acrylic resin emulsion, etc., (E) 0.1W10wt.% polymer, e.g. PE, PP, etc., (F) 0.1W5wt.% nonferrous metal rust preventive agent, e.g. colloidal silica, etc., and (G) the remainder of water.