MIL-PRF-81329D, MILITARY SPECIFICATION: LUBRICANT, SOLID FILM, EXTREME ENVIRONMENT, NATO CODE NUMBERS S-137 (18 SEP 1998) [SUPERSEDING MIL-L-81329C]., This specification covers the requirements for one grade of a solid film lubricant for use at temperatures ranging from -185 deg C to 400 deg C. This solid lubricant is identified by NATA symbol S-1737.