My helpful son topped off my '98 mustang GT with a quart of synthetic ATF...the other 4 quarts is normal 10W-40 oil - - do I need to run to the station and get it changes or can I wait until I change it on schedule - about 2,000 miles from now?
lol my mom did that to her old plymouth breeze. personally i'd change it. atf is thinner than motor oil and probably not designed to take the heat and abuse oil does
ATF has been used as an engine cleaner, just like the Motor Flush you can buy at an auto parts store. Chances are that it has worked any gunk in the engine loose. It's not a horrible emergency but I wouldn't drive it too far.
Put some fresh oil and a new filter on. Just use some cheapo oil & filter. Then change the oil & filter again after a few days and use the stuff you normally use. That'll get any residual out and it'll be fine.
ATF makes a horrible engine oil. it is a commonly held myth that it contains more detergents then motor oil. at one time it may have been true, but with SM oils, it couldn't be more from the truth.