Hello, We all know that, in Commercial aviation, we use Hyjet (SKydrol or 500B4). and in military we use MIL-H-83282 (red oil). what are the main reasons? MIL-H-83282 has a synthetic hydro carbon base and contains additives to provide the required viscosity and anti wear characteristics, which inhibits oxidation and corrosion. and having a temperature range of -40 Deg C to +135 Deg C, and its a fire resistant fluid. Why are we not using MIL standard fluid for Commercial aircraft? What are the defined standards for Hydraulic systems in Commercial and Military? (where can i get that info. CS/FAA-25?) Difference in Properties of both fluids? Thanks in Advance.