Abstract: A fluid, highly heat stable, insulating composition is made by admixing: (A) from 9 mole % to 12 mole % of selected unsaturated cyclic dicarboxylic acid; (B) from about 15 mole % to about 20 mole % of an unsaturated aliphatic dicarboxylic acid; (C) from about 35 mole % to about 40 mole % of an aliphatic dihydric alcohol; (D) from about 25 mole % to about 40 mole % of diallyl phthalate copolymerizable monomer; and (E) an inhibiting agent, to provide a polyester; and from 15 parts by weight to 30 parts by weight of hexa methoxy methyl melamine per 100 parts by weight of polyester.