Depending on what the can and its pump are made out of, maybe. Acetone is a pretty aggressive solvent and can destroy plastic and rubber parts, so the pump and/or its seals may be damaged. Make sure the can seals when not being pressed, the acetone may evaporate or the vapor pressure may push fluid out of the container otherwise. Be sure to shake the container to mix the acetone and ATF together before using it. They don't mix well, the acetone settles to the bottom over time. And yes, the mix is 50/50.