Strut bearing noise

[mf5781]

Mine is a 2004 Mazda 3 sedan with about 52,000 km. When the steering wheel was turned, I heard a grinding noise from the front, liked quack-quack-quack. A non-Mazda mechanic said it's the strut bearings dried out. He put some grease in them. It seems to stop the noise. Can someone explain to me why the bearings dried out so early? Why is there no rubber cover to seal the top of strut on Mazda 3? Can the grease cure the problem or do I have to replace the bearings? If I have extended warranty with Mazda, will the replacement be covered?

[bluntman]

So early? My dad's 3 had that problem within the first year of ownership of his 2004. It was replaced under warranty back then.

[MidnightSpeed]

Is that what that is.. thanks - car's going in tomorrow too :)