I dont think the ATF will clean as quickly as hoppes, but it will clean over time, I believe, as effectively. I have no problem leaving ATF in the bore for as long as a year, while I would want to get the Hoppes wiped out after a day or so, once the expansion cracks have released their contaminants. Break Free is a great product also and provides outstanding corrosion protection, but if I can be crafty and use an automotive product, I will everytime for reasons of economics, as well as, I know the auto industry invests and has invested millions and millions of $$$ on car care products. Listen to the auto techs. They have inside info on the lates wonder chemicals.
"I love the smell of Dexron in the morning" lol