Mobil Aero HFA is a premium quality fluid that meets the quality requirements of the U.S. Military specification MIL-H-5606A (now obsolete). MOBIL AERO HFA has a very high VI and is suitable for use at temperatures down to -54 ºC (-65 ºF). MOBIL AERO HFA fluid is no longer used by the U.S. Military, it is still used in some older, small private, and commercial aircraft. MOBIL AERO HFA is also used in industrial and commercial equipment requiring good fluidity at very low temperatures, where Mobil Aero HFA provides long, trouble-free service over a wide range of operating conditions.