Ummm oil is good, but fish oil or something that coats and sticks evenly would be a bit better, Lanolin oil !?, Chain lub is probably too sticky ichy to evenly coat.
Definitely check before paint, paint can cover a multitude of sins. (for a while)
And Bfit is right (oh bite my tongue) about putting pressure in - only a few psi, tub of water and wash up detergent.