You should use
only sewing machine oil, including for cleaning the surface of the machine. There are different brands, and I don't think they're all the same, I have no brand recommendation, I just make sure it says sewing machine oil and that it's clear. You can use petroleum jelly (I think the original formula for Vaseline) to re-grease the motor (there are grease cups on the underside). I look here for parts first:
https://www.vintagesingerparts.com/
I have no affiliation with the company. And you can find the user and adjuster's manual for your machine there.