Wiper 'spoilers' are indeed to provide downforce. Overhere we usually see these integrated in the wiper itself (the part you replace) and not directly on the arm (which is fixed to the car).

It's there to combat a problem which happens when you either drive fast (100+mph) or have a very strong headwind and need to use the wipers.

These conditions can cause air to 'collect' in front of the wiper blade. The passenger wiper blade can deflect this air to the side of the car, but the drivers blade can't.

On the downward movement of the wiper this air pressure can cause the wiper blade to 'lift' a little and the wiper then 'bounces' while going downward. No wiping-action being preformed anymore and visibility suffers.

If either of these conditions (fast drive or high winds) don't happen very often to you then a 'non-spoiler' type will work fine. The wiper-spoiler stuff (as found on nearly all European cars) is actually more of a patch until someone comes up with a real solution..

A problem with the spoiler setup is that the downforce can press the wiper blade down onto the glass very firmly (to stop it 'hopping') and the wiper motor can't get them moving enough anymore.

This happens on my T4 where the wipers are pretty much useless above about 110 mph as they move very slowly and don't get all the way down anymore. I just see it as a 'built-in' safety feature that you shouldn't drive this fast in the first place if you need to use your wipers.. :)

Bye, Arno. --
S40 T4M with TME ECU upgrade, running on Toyo Proxes T1+ 215/40R17 using O.Z. F1-Cup wheels