Abstract: A coolant comprising water and one of 1-methoxy-2-propanol, 2-methoxy-1-propanol or mixtures thereof, resistant to degradation of fluoroelastomers and which is inhibited against corrosion of ferrous metals, aluminum and solder is disclosed. The desired coolant is prepared by reacting in situ or adding the reaction product of one or more phosphoric acids and an inorganic base selected from potassium hydroxide, sodium hydroxide or mixtures thereof, and optionally contains, as a copper or brass deactivator mercaptobenzothiazole, a benzotriazole, a sodium or potassium salt of mercaptobenzothiazole or a benzotriazole, or mixtures of these, wherein the pH of the coolant is adjusted to between about 6 and about 9 by balancing the relative amounts of phosphoric acids and inorganic bases to attain said pH. For example, about 53 parts 1-methoxy-2-propanol, 46 parts water, 0.8 parts K.sub.2 HPO.sub.4, 0.1 part orthophosphoric acid and 0.