Tom and Ray run through the entire table of elements trying to identify the white powder in Ann's Subaru's radiator. If only they could put that much effort into figuring out why the car is blowing through heater cores! Elsewhere, Jamie wants to achieve his modest life ambition of owning a truck with power steering, but doesn't know whether to also go diesel; Dr. Gary is having doubts about his professional services exchange with his mechanic neighbor; Doug needs to decide whether he wants to become the "Chuck Yeager of CV joints", or risk being stranded on a railroad track; and Anna discovered a rat in her Civic's passenger seat--how did it get there? All this and more, this week on The Best of Car Talk.