The critters can smell that junk.
the critters smell EVERYTHING! there is nothing that you can use on a firearm that the critters are not going to be able to smell. with noses that are somewhere between 4,000 and 50,000 times more sensitive than ours. just think about you dog next time you cook up a nice juicy steak, or on the other end, cauliflower! sometimes, it is a blessing not to be able to smell very well. for us, their noses are a curse, for them, it is how they stay alive.
as far as atf goes, it is a wonderful lubricant, and a heck of a cleaner. when i am shooting lead loads, my version of ed's red is only 3 things. mineral spirits, kerosene, and atf. it works great for removing powder residue, and is very inexpensive to make. as a lubricant, it flows very well at any sub zero weather that 99.5% of us will ever hunt in, and the other .5% i honestly do not know. i do know that @ -25f, you can start up a car, drop it in gear, and the transmission works. in both standard and automatics (many modern standard transmissions use atf). in my years of shooting, i have used many, many oils. regular and synthetic gun oils, marvels mystery oil, stp, mobil 1, castrol gtx, and on and on. unless it gets really cold out, almost anything works. guns are made from relatively hard steel, and they never move any whers nearly as fast as a piston @ 6000 rpm. all of them worked fine. if i was going on a dangerous game hunt, or Alaska, i would not take a chance on ANYTHING going wrong, and i would use a synthetic gun oil. it is not worth taking the chance that your gun will not fire when a brown bear is charging you and it has been freezing rain half the day. or when a lion suddenly appears in the tall grass at 15 yards. you do not try to save $5.00 when it has taken $20.000 to get there, and your life is on the line.