You drive the same route to work every day—same open stretches, same intersections, same stop-and-go. But today there's a subtle discord in the usual harmony, a blip on your vehicular radar, a bad vibe in your mechanical karma. Shifts seem oddly late and soft. Later, as you pull into the drive, you sense something peculiar. Letting your car idle, you pull the dipstick out of your auto transmission. Fresh automatic transmission fluid (ATF) is bright red and has a distinct petroleum smell. Your dipstick shows a low level, is the color of institutional linoleum and smells like the bottom of a barbecue pit after a biker wedding. Your transmission fluid is badly in need of changing, and the tranny may already be damaged.