Hi Marcus
Nice build you have going on.
A metal shaping 'god' friend of mine (Mike Roberts - facebook Hammer Works) put me onto a metal protection fluid called Epiphos. It's a quick drying phosphoric etch transparent primer thing... For most bits I use a small domestic spray bottle, squirt bits lightly and then wipe smooth/off with a rag. It dries very quickly, lasts for months inside and can be welded through without issue. The guy that acid dipped and fine media blasted our racecar shell, sprays it inside and out immediately after blasting. It's better than the Henkel 'Keyphos' I previously used.
http://www.chemetall.co.nz/product/epiphos