Gentlemen.
I swear black & blue that pipe cleaners work in those oil feeders. The big fluffy white ones are best. (We all know oil wont capillary flow up a green one).
Done it myself a few times. Didn’t invent it myself, one of the old guys in that vintage of machine showed me it. I recall seeing some of the original wicks, having a small copper strand of wire included in them, with the cotton string woven / wrapped around that, so that they could be shaped and hold there form.
Regards Phil.
P.S (On Edit). That didn’t answer you original question. We all got thrown by the mention of pipe cleaners.
Once upon a time, that kind of oiler used to use a length of cotton string, called a “wick” dipped into the oiler and up and over, and down into oil port. So it was very common. You had to “wet” the wick when you installed it. I never quiet understood the science of it. But it was called capillary action, where the length of string / wick was longer going down into the port, than the height of the head it had to draw the oil up. I imagine it like siphoning.
It was also considered that the string acted as some kind of filter to the oil, where heavy particles would get trapped in the fines of the string. That’s why they were replaceable.
It was also considered that when you forgot to lubricated the machine, that the residual oil in the wick would prevent a bearing from running totally dry.
It does work to slowly feed the oil to the required point. The other ones, just the plain spring lid cups, you gave them a shot of oil, and it went away immediately.
Barry Mentioned Gits
http://www.gitsmfg.com/gits-catalog.asp
There’s some information about wicks and oil feeders there.