Maintenance Level 1 (ML1) AMTP Evaluation Practice Test

In hydraulic systems, fluid choices are governed by compatibility with seals and materials, and by performance across the operating temperature range. If the manual allows both petroleum-based and synthetic fluids, it means either type can be used as long as it meets the system’s specified performance requirements. Petroleum-based fluids are widely used for their cost and availability, while synthetic fluids typically offer better high-temperature stability, oxidation resistance, and sometimes improved lubricity. The key is ensuring the chosen fluid meets the approved specification for that system. Water-based fluids are not generally authorized for most hydraulic systems due to risks like corrosion, reduced lubrication, and potential microbial growth unless the equipment is specifically designed and approved for them.