I've read some conflicting dos and don'ts when it comes to sending used oil to Blackstone. I've got my sample ready to ship and I have decided to use a 14x14x14cm box. I will need to fill out a customs declaration. I will be sending it via FedEx ground. Do you indicate that it is USED OIL or what do you write. I see on the other thread that you shouldn't write "used" and then a post that says its okay. Any input would be appreciated.