I would suggest you use a good grease instead of oil. Personally, I use Super-Lube synthetic grease for my boring heads. The reason for using grease instead of oil is retention; the grease will not be slung as the head spins, as oil would be. If you go with grease, you only need a light coat in the leadscrew and a very light coat on the sliding ways. I also use a very light coat Camellia oil on the body and in the holes for the boring bars to keep rust at bay. Then I just quickly wipe it down before use. I currently own 5 boring heads and all of them work perfectly and have done so for decades so I guess this works okay for me.