I accidently used about a quart of Mercon ATF in my '01 Taurus which of course calls for Mercon V ATF. Should this be something to be alarmed about, as in flushing the Tranny or is it something I can let slide? Thanks for your input/advice.
I dont think it is a major disaster. Tranny holds around 14 qt, so 1 qt "regular" Mercon shouldnt make much of a difference. None the less; you may want to think about a fluid exchange and filter if it hasnt been done in a while.