GPL 207 for High Vacuums.
Krytox Grease is used in many lab applications for greasing joints/connections. Krytox provides excellent performance in temperatures ranging from -75 °C (-103 °F) up to 399 °C (750 °F). One of the key advantages of Krytox Grease is that it is non-flammable and chemically inert. It is also chemically insoluble in just about all solvents.