They don`t actually wipe the throws or cranks, what they do is wipe off the oil flying around the crank that is actually spinning w/ it. Dragging it w/ the crank (like a rope) costs a little h.p. and keeps oil in motion, instead of falling or draining back to the sump. not as big a problem on street cars, as it is race, high RPM engines. Girdles help a little in that department too.
