MIL-PRF-6083 Hydraulic Fluid, Petroleum Base, For Preservation And OperationThis specification describes the characteristics and provides the requirements for one grade of petroleum base hydraulic fluid for use in the -54??C to +135??C temperature range \(see 6.1\). This fluid is rust inhibited and used both as a preservative for hydraulic systems and components as well as being an operational fluid. This hydraulic fluid will not be used for aircraft systems, aircraft ground support equipment, or the preservation of aircraft components. The hydraulic fluid is identified by Military Symbol OHT and NATO Symbol C-635.