The word antifreezes is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 24
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (35 words)
aeriest, antsier, arenite, earnest, eastern, eeriest, entrees, entries, faeries, fainter, fairest, fireant, freesia, freezes, freezie, friezes, nastier, nearest, refines, reseize, restain, retains, retinas, seriate, sneezer, snifter, stainer, sterane, teenier, trainee, triaene, trienes, zaniest, zeatins, zestier