What is this and what goes in it?

[Boatcop]

1975 Spectra, 455 Olds, Jacuzzi pump.
Coming horizontally out of the bottom of the distributor is a slender tube with a flip cap on it. I presume this if some kind of oiler for the distributor shaft.
Any clue on what kind of oil or ??? goes into this? I tried to use an eyedropper to add some basic 30 weight, but it it didn't flow in and only took a drop or 2.
Any help from the Jet Gods?

[AZKC]

Old School :D It is an oiler for the distributor. I had some on some old Mallory dual points. Probably clogged might try cleaning it out but probably need to tear down the Dizzy and cleanup the passage from the inside/out.

[SmokinLowriderSS]

Yes, REALLY old school. AZKC's right on it I believe, manual dist bearing oiler.

[Captain no fun]

Use a zoom-spout, and sewing machine oil. You can obtain @ a sewing machine repair shop. You could look on E- bay for a used mallory or MSD, to lose the points, or use a pertronix system for more reliable spark.