Abstract: Both a method and a kit for testing the fitness of a polyolester lubricant of the type used in a refrigerant compressor are provided. In the method of the invention, a solution for indicating an excess acidity of the polyolester lubricant is obtained by mixing a color acidity indicator, such as alizarin, with a sufficient amount of an alkaline to neutralize the inherent acidity of the lubricant. The resulting solution changes color only upon the presence of an excess acid condition associated with a compressor malfunction, such as burn out. Both the method and the kit are particularly well adapted to determine the fitness of polyolester lubricants of the type prepared by the reaction of trimethylolpropane with a mixture of a branched and a linear acid.