Radiator Fan

This fan is designed for a car's radiator, to be placed right behind it, so that it sucks air from the radiator. (it spins counter-clockwise, as viewed in the above photo) The person who send me this photo has a interesting question. He bought the fan as pictured above. However, some car guys told him that the blades is installed backwards.

So, he reversed the blade, resulting in the following photo. The blades still spins counter-clockwise (because the motor in the center remains the same), but now the blades are scythe-like.

The question is, which way is the right way? (i.e. more efficient for sucking air)

I have no idea, but i'm guessing the car guys are right. I kinda think that when blades are in this way, it scoops the air like a spoon. If you know, please comment.