Mobil Aero HF Series aviation hydraulic fluids are designed to meet the demanding requirements of commercial and military aircraft applications. These high quality formulations have a long history of excellent performance and provide long, trouble-free service over a wide range of operating conditions.

Product features and potential benefits include:

Features Advantages and Potential Benefits
High Viscosity Index (VI) Allows equipment operation over a wide range of temperatures
Excellent low temperature properties Provides high performance operation in low ambient conditions
Good chemical and oxidation stability Resists the formation of acidic constituents, varnishes, and deposits
Meets "super clean" requirements of U.S. Spec. MIL-PRF-5606 (Aero HF) Ensures reliable performance of pumps, servo-valves and other hydraulic system components


Mobil Aero HFA is a premium quality fluid that meets the quality requirements of the U.S. Military specification MIL-H-5606A (now obsolete). It has a very high VI and is suitable for use at temperatures down to -54 ºC (-65 ºF). While this quality fluid is no longer used by the U.S. Military, it is still used in some older, small private, and commercial aircraft. It 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.

Mobil Aero HF is a premium quality fluid that is approved against the most current version of U.S. Military specification MIL-PRF-5606. It has physical properties very similar to Mobil Aero HFA, and also meets "super-clean" requirements required by modern aircraft hydraulic systems. It is intended primarily for military aircraft, but it is also used as a hydraulic fluid for small private and commercial aircraft, and as a strut fluid in landing gear of large commercial aircraft. It is a NATO Code Number H-515 fluid.


Mobil Aero Grade HFA HF
MIL-H-5606A (obsolete) quality level X
MIL-PRF-5606 approved X
NATO Code H-515 X

Typical Properties

Mobil Aero Grade(1) Test Method HFA HF
Color Visual Red Red
API Gravity 30 29
Specific Gravity, 60ºF/60ºF ASTM D 4052 0.872 0.872
Density at 60ºF, lb/gal ASTM D 4052 7.26 7.26
Pour Point, ºC ASTM D 97 -64 (-60 max) -62 (-60 max)
Flash Point, COC, ºC ASTM D 92 107 (93 min) 107
Flash Point, PMCC, ºC ASTM D 93 92 96 (82 min)
Acid Number, mg KOH/g ASTM D 664 0.03 (0.2 max) 0.04 (0.2 max)
Barium Content, ppm ASTM D 5185 - ‹1 (10 max)
Kinematic Viscosity, cSt ASTM D 445
at 100ºC 5.2 5.2 (4.9 min)
at 40ºC 14 14.0 (13.2 min)
at -40ºC 450 (500 max) 450 (600 max)
at -54ºC 1900 2000 (2500 max)
at 130ºF 10.4 (10.0 min) -
Viscosity Index ASTM D 2270 370 370
Low Temperature Stability FTM 791.3459 Pass -
72 hours at -54ºC FTM 791.3458 - Pass
Copper Corrosion, 72 hours at 135ºC ASTM D 130 1b (2e max) 1b (2e max)
Oxidation Corrosion Stability, 168 hours at 135ºC ASTM D 4636 Pass Pass
Water Content, Karl Fischer, ppm ASTM D 6304 50 (100 max) 50 (100 max)
4-Ball Wear Scar, 1 hour, 1200 rpm, 75ºC, 40 kg, mm ASTM D 4172 0.6 (1.0 max) 0.6 (1.0 max)
Evaporation Loss, wt % ASTM D 972
6 hours at 71ºC - 12 (20 max)
Particle Count Auto Counter
5-15 microns 1000 (10000 max)
15-25 microns 100 (1000 max)
25-50 microns 30 (150 max)
50-100 microns 5 (20 max)
100+ microns 0 (5 max)
Particulate Contamination, mg/100 mL ASTM D 4898 0.2 (0.3 max)
Foam, Seq I, mL/mL ASTM D 892 36/3 (65/0 max) 37/2 (65/0 max)
Nitrile Rubber L Swell, 168 hours at 70ºC, % FTM 791.3603 27 27 (19 to 30)
Shear Stability, Option B, Loss in KV at 40ºC, % ASTM D 2603 15 max 15 max
Bulk Modulus, Isothermal Secant at 40ºC, 4,000 psig, psi 200,000 min 200,000 min
(1) Values not identified as min/max are typical and may vary within modest ranges


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