AeroShell Fluid 4 is intended for use as a hydraulic fluid in undercarriage retraction mechanisms, flap jacks and control mechanisms, brakes, shock absorbers, automatic pilots, oleo legs, tail wheels, servo units, etc. It is also suitable for lubricating de-icing pumps and gearboxes. AeroShell Fluid 4 should be used in systems with synthetic rubber components and must not be used in systems incorporating natural rubber. The latter systems require castor base fluids with which AeroShell Fluid 4 is not interchangeable. AeroShell Fluid 4 is compatible with AeroShell Fluids 31, 41, 51, 61, and 71, although it is not recommended that AeroShell Fluid 4 is used in systems which require the use of a superclean fluid nor should it be mixed with superclean fluids for operational reasons. Chlorinated solvents should not be used for cleaning hydraulic components which use AeroShell Fluid 4. The residual solvent contaminates the hydraulic fluid and may lead to corrosion. AeroShell Fluid 4 is dyed red for identification purposes. The useful operating range is -54 degrees Celsius to 90 degrees Celsius. The useful operating temperature range pressurized is -54 degrees Celsius to 135 degrees Celsius. Meets MIL-H-5606A (obsolete).