I picked up a set of vintage Master Craft capillary precision oilers. Set includes 2 glass tubes that are each open at one end with fine needles attached to the other ends (the oilers) and a glass tube that is open at both ends with a short 1/2" or so rubber sleeve that fits over the end of the filler tube.

Instructions on box aren't clear. They say:

1. Press plastic top of filling tube lightly over needle end of oiler.
2. Draw oiler half full then lift oiler from bottle and draw oil to tip end.

Not sure what this means. Does "plastic top of filling tube" mean the needle of oiler goes into one of the open ends of the filler tube? Where does the rubber sleeve come into play, and where does the oil bottle come in? Also, is the oil drawn by physically sucking through the tube like a straw?

Any explanation and/or illustrations appreciated.