Roof whirlybird question

[jackrabbit000]

We have a couple of aluminum whiirlybirds on our roof for ventilation. These have been up there for around 6-7 years. The question that I have is, do the bearings in these things ever need to be greased or lubricated? Some days when it gets super windy I always have this feeling that the bearing might fail because the thing is spinning so fast. Has anyone ever have one of these things fail on them?

[Pete_Coach]

When they fail they make a noise and begin to wobble. You will know. There have been these things on roofs for upwards of 20 years without a problem. Do they fail yes but, if it works , leave it alone.
When they fail replace them with a cupola type or, a ridge vent type if you are re-roofing at the same time.