Shimano Deore hubs with operating lube ports
 

Hubs are 20 years old. They have black caps/rings on the ends of the hub, each with two holes, and an "open" arrow (counter-clockwise, if I remember correctly). How is one supposed to open and close these? Special spanner tool? And use what to lube them (oil?) injected using what? I have a cute little Sharpie-size "ballpoint pen" oiler made by General that I found at McMaster-Carr.

Can't find any Shimano literature about them; I guess it's been too long! I like the old-style metal clips in the middle of the barrel that my Campy Record hubs have.

Thanks,

I seem to remember that those are dust caps and the "open" position is to remove them.

The memory is the first thing to go...

I just use my fingers. The problem with my hubs (also 20 years hold) is that the dust caps have been popped in and out so many times for maintenance that they are loose and the whole dust cap rotates instead of just the part that opens the hole.