Gelest offers four different classes of silicone fluids: thermal, conventional, fluorosilicone, and low temperature. Thermal silicone fluids are described as aromatic siloxanes. The phenyl groups enhance oxidation resistance, thermal stability, and shear resistance. The phenyl groups offer better protection of the chain Si-O-Si-O by steric hindrance and phenyl itself has a low susceptibility to oxidative attack. The service temperature ranges from -55 ºC to 290 ºC for high phenyl content silicone fluids. The polyphenylmethylsiloxanes are stable for thousands of hours at 250 ºC in closed oxygen free systems.