For the headstock oil cups I’d suggest Shell Tellus 27, for the bed-ways etc. a straight mineral oil will do. Engine oil is not the best but any lubricant is better than none. Also attend to the felt wipes on the saddle to limit the ingress of small particles.
Sources of supply are another matter, if you have any manufacturing in your area try seeking out skips/bins with swarf in ’em, that in turn should lead you to the people who actually make things, if you explain what you are about and grab their interest you are “in”!
If there is a university nearby that hasn’t gone all PC, (in more ways than one), or “arty” you will find that many departments have workshops. If they do any sort of engineering you have a very good chance. Try to see the Chief Technician.
Finally there are the local secondary schools, a few still have craft rooms and the Boxford was a popular choice of lathe. Ask for the teacher who does “resistant materials” or the technician.
After all, with reasonable care a ¼ pint will probably see us all out!