6 Pack Needle Tip Squeeze Bottle 50mL(1.69 OZ), Precision Gun Oil Bottle, Needle Oiler Bottles for Craft, Glue, Paint, Hinges, Sewing Machines & More - LDPE Material with Premium Seal

Drill a small hole off center of the brass insert until you get to the oil cavity and you can use a small needle dispenser to fill it with oil. I use these: https://www.amazon.com/dp/B0F18NX1PZ For the oil, you can use a light machine oil. The stuff sold for paper shredders works well.