The biodegradable hydraulic fluid covered by this specification is military unique due to the requirements for low temperature performance and storage stability. Military applications generally necessitate that the hydraulic fluid perform at lower temperatures than commercial applications, and the storage period of the hydraulic fluid for military applications can be significantly longer than the storage period for commercial applications. The hydraulic fluid is intended for use in the environmentally sensitive areas such as construction, forestry, river, and mining. They are applicable to use in the construction equipment, bridging, tactical vehicles, shipboard hydraulic systems, and hydraulic systems for metal tool applications. If used in any other equipment or hydraulic systems, a study should be made to determine its applicability in such mechanisms or systems, particularly in the area of elastomer compatibility and operation at high and low temperatures.