What should be used to flush a hydraulic system serviced with MIL-H-5606 hydraulic fluid?

When flushing a hydraulic system serviced with MIL-H-5606 hydraulic fluid, oil-based cleaners are the appropriate choice. This is because MIL-H-5606 is a petroleum-based hydraulic fluid, and using an oil-based cleaner ensures compatibility and effective removal of contaminants without risking chemical reactions that could lead to damage or system failure.

Oil-based cleaners are specifically designed to dissolve oil and grease, helping to mobilize and remove debris from the hydraulic system without introducing moisture or other chemicals that could compromise the integrity of the hydraulic fluid. The flushing process is crucial to maintaining the system's performance and longevity, as any remaining contaminants can cause wear and reduce efficiency.

While other options, such as water or alcohol, may seem like solvents for cleaning, they introduce moisture into the system, which can lead to corrosion and other failures. Similarly, using substances like naphtha could pose risks of improper chemical reactions, and acetone is a strong solvent that may damage seals and other components. Thus, oil-based cleaners align best with the requirements for flushing systems using MIL-H-5606 hydraulic fluid.