ATF is great in transmissions where heat, friction, and hydraulics are in need of a quality oil. The thing is, sewing machines are not transmissions and do not function like transmissions.
The clear oil used as sewing machine oil is designed to work in sewing machines and does that very well. Any machine that sits for any lengthy period of time should be oiled before use as the oil, any type, will run off or evaporate. Some faster than others, but it does dry out.
I have used ATF as a cleaner in really stubborn machines, but when finished I cleaned it out and re-oiled the machine with Tri-Flow and never looked back.
I make suggestions as to what oils / greases to use based on my experience, but I know people will use what ever they want. I suggest Tri-Flow.
Joe