which is employed varies with the amount of hydroxyl group replacement desired for purposes of this invention the trimethylchlorosilane is employed in amounts from about 9 5 to 25 5 weight percent of the weight of the hydrolyzate more specifically for polycarbonate additive purposes the amount of trimethylchlorosilane chainstopping agent used ranges from about 11 4 to 19 by weight of the total weight of the hydrolyzate providing a trimethylsiloxy unit content for the fluid of from about 12 to about 21 percent by weight after agitating the mixture for about one hour the mixture is washed with for example 15 sodium sulfate until essentially neutral and the aqueous bottom layer is separated and discarded the remaining organic layer is washed with for example sodium sulfate and the organic solvent and residual water is stripped under vacuum e g 25 to 30 mm hg at about 150 u00b0 c the remaining phenyl containing organopolysiloxane fluid is characterized by formula i hereinabove wherein x and y are values sufficient to provide a phenyl content of from about 40 to 80 weight percent and is especially well suited as an internal mold release additive for polycarbonates since the fluid is highly soluble in polycarbonates and moreover retains the desired.