A multipurpose functional fluid which is comprised of a major amount of a hydrocarbon oil and a minor amount, sufficient to improve characteristics of the fluid of a novel additive. The aditive is comprised of a calcium salt complex, a group II metal dithiophosphate salt, a borated epoxide and a carboxylic solubilizer. The calcium salt is preferably in the form of an overbased calcium sulfonate salt, the antiwear agent is preferably in the form of a zinc dithiophosphate salt, the borated epoxide is preferably the reaction product of boric acid and a 16 carbon 1,2-epoxide and the carboxylic solubilizer is preferably in the form of a reaction product of an acylating agent containing a substituted hydrocarbyl-based substituent containing about 12 to 500 carbon atoms. Other components such as viscosity improvers and anti-foaming agent are generally present in the fluid. The resulting fluid has improved low temperature fluidity and filterability, improved EP/antiwear performance, excellent friction improving properties, antichatter capability as well as being capable of passing hydraulic/transmission tests, power steering and brake capacity tests. These features are maintained simultaneously without harming other desirable performance characteristics of the fluid. The EP/antiwear performance characteristics are maintained concurrently with the anticorrosion characteristics and transmission performance capabilities. The improved water tolerance is maintained concurrently with the improved EP performance characteristics.