[serf]

doing this on a fan that used a dry lubricant can burn a wire lead from increased startup torque requirements to get it spinning.

it's not bad advice but it's worth noting that petroleum jelly is pretty thick compared to a machinists' oil or dry graphite.

[userbinator]

The leverage the motor exerts is huge relative to the shaft, and chances are that when the bearing is chattering audibly, it's already been running dry with much higher friction for a while, and worn enough that you'll need the extra viscosity of a grease to fill the clearance.

[magicalhippo]

Then there are the fans with magnetic bearings. Had a few that started making noise but never figured out from where, given there are no touching parts.

[jijijijij]

I think magnetic bearings necessarily also got touching parts.