At the basics it's very simple: Drop of oil each on the bearings. Where are the bearings? The 'caps' on the front and back of the motor held on by machine screws, that trap the fan shaft in place. You want the oil to go onto the bronze colored (it's actually bronze!) bushing held on by those grey zinc caps. For reference, the zinc caps are the bits held on by the two screws in the motor that are left after you've taken the motor out of the plastic housing at the end of the instructions.
I went one step further: I took that screw apart (it's a nut and a screw, use a small channel lock and a screwdriver on the other end), removed the bearing caps and the fan shaft, and soaked the bushings in motor oil. I used 10-30 but whatever works. I put them in a dish and used a vacuum container to help get oil into those bushings, took them out, cleaned them off, reassembled and my partner's fan is super quiet now. (No vacuum sealer/container? Just soak overnight.)
