Wiper problems of the 2006 Mazda RX8

The driver and passenger side sun visors have split open and flipped down spontaneously blocking my vision while driving. I've had multiple instances of the driver and passenger side sun visors splitting along the seams, causing them to disrupt my visibility of the road. I had my Mazda dealer replace the defective visors while under warranty on multiple occasions, but the defect continues to occur. Every single time I was informed that splitting sun visors was a common occurrence on all Mazda RX-8s. The lubricant inside the hinge of the visors would solidify during hot weather and cause the spring to expand, thus splitting the plastic sun visor along the seams. Since the visors hang in the downward position once the plastic has split, the only way to not obstruct my vision while driving is to completely remove them from their mounts. This, however, causes the added problem of not having any way to block direct sunlight that can shine on your face in the early morning or evening. The only recourse given to me is to continually replace the sun visors at $75 each every few months. I find that this is a potential safety hazard that should be addressed. Any insight would be greatly appreciated.