Where did the oil leak out of? Hopefully the air line hole. If it leaked from another location the shock probably isn't usable.
A vacuum as suggested works great. I've done several sets.
it came out during shipping from another member did a swap long for short.
Turn the shocks upside down in your vice when extracting and right side up when filling. I had the connectors from a compressor kit to hook everything up. I just installed air ride on my bike but can't test it out yet because of the snow.