Ship suspension international

Freight companies are ok. Just do a check on their website for pricing. 

Empty oil and gas if you want to be sure not to get in trouble but typically its just fine. Not like they look, but you do agree not to ship hazardous material. 

I have shipped mine multiple times between US and Europe. 

I've flown with suspension (packed in a guncase) international before. South Africa to LAX (+ - 5 yrs ago)

Freight companies will ship it. Check with them but I'm sure you won't have to drain and empty the gas. Nitrogen is inert and is very stable. We know that, they don't, so don't tell them about any gas.

Oil in the suspension is fine. Get a gun case, make sure the suspension is clean and pack it in and take photos. 

A freight company will have a look and only then do you seal it up infront of them. 

Get insurance for your suspension. Shipping and insurance gonna cost you a bit...I'd say around $250 - $350. Don't hold me to that pricing but I'm sure I'm close.

You don't need a guncase. I just remembered that my buddy flew international after me and he took suspension in one of the Pro Circuit suspension boxes. (Cardboard) I helped him wrap it with bubble wrap.

I like a guncase because it is solid and your expensive suspension will be safe in transit.

Guncases can be pricey so shop around for second hand ones. You local Gunshops / firearm shops are the best to phone when looking for one. 

Not sure it's the best moment to ship suspension in and out of the States... Who knows what can happen and how much it can cost to get your guncase back...