Aeroshell 4 is what is commonly known as 5606. It has nothing in common with any form of ATF .
MIL-H-5606A (now G and H), There are claims that MIL-H-5606 has been replaced with MIL-PRF-83282 and MIL-PRF-87257. That's just not so. 5606 is in common use.
The bottom line is that 5606 works well at -65ºF, and is compatible with nearly all forms of synthetic rubber seals.