Well, here's my story. Trying to find the answer on the net is one of those times you have to be an attorney to figure out what you're reading. Call the shipper and talk to 5 different people, you'll get 5 different answers. My favorite answer was, "As long as you can't smell it, it's fine!" I normally ship FedEx ground, generally due to the package size and cost. When you ship through eBay, once you go to print the shipping label, any restrictions will pop up and you have to either verify you meet the criteria, or you can't ship. Nothing has ever popped up. Plus, a bazillion of these things are sold and shipped through the system, so I just don't worry about it.

Personally, I ship DRY tanks. I close the vent screw in the cap on the tank and make sure the cap is tight. I put the tank in a strong, plastic trash bag and seal it. I ship in an over-sized box so I have plenty of space for padding. I print the label, slap it on the box and ship it. I have no clue how everyone else does it, but if there was any flak, I'll guarandamnty you, eBay would be all over it. Heck, I have a brand new flare gun I bought for my boat. Ebay jumped all over my butt and pulled the listing. I've had that happen with quite a few items. Never heard so much as a hiccup regarding fuel tanks. Frankly, it surprises me, but it's a pleasant surprise.