A two part curable composition comprising organosiloxane polymer; water; an organosilane such as hexamethyldisilazane (HMDS) or vinyltrimethoxysilane; crosslinker; adhesion promoter and catalyst; and optionally comprising plasticizer; colorant and filler. The first part can comprise organosiloxane polymer and water. The second part can comprise crosslinker; adhesion promoter and catalyst. Either or both parts can optionally further comprise an organosilane such as hexamethyldisilazane (HMDS) or vinyltrimethoxysilane; plasticizer; colorant and filler. Cured reaction products of the two part curable organosiloxane composition has good adhesion to metallic sealing surfaces and good resistance engine oil and other automotive fluids. Cured reaction products of the two part curable organosiloxane composition can surprisingly retain physical properties after long-term exposure to temperatures between 200° C. and 250° C. and can retain physical properties after exposure to temperatures between 250° C. to 300° C. for short periods.