Once tubing is ran and hooked up, loosen fitting at gauge and allow oil to pass through for removing air in line.
I'd use copper, something like this:which is best for oil lines copper lines or nylon? where do you find copper lines? thanks
Are you sure about that? "Work Harden" is exactly what it says and it would have to be "Worked" (Machined, hammered, etc in order for it to become hardened. Just being in a static position will not cause hardening. "Age Hardening" would be another form, but that takes heat-a lot of heat.Copper will work-harden and eventually fail.
If you use the correct brass fittings and a firewall grommet, the nylon would be fine.