you dont need to empty them the oil flows thru them from side(in) to top(out)
im sure i posted here the other day but its not here lol must of closed the page or got side tracked
i said ""dont put them in a vice it makes them all scrap the burnt on oil vapour on the outside once that hits the outer case there stuck and scrap 🙂
new ones are cheap
http://www.ebay.co.uk/itm/111396481222?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
you can put them in degreaser over night then blow them out with an air line from the top that will clear and cack on the inside
and you can prime them with oil before fitting if you choose or prime in the engine before running for the 1st time
