Yep, all metal parts from china come with an oily film to prevent corrosion during transit. So you need to wash them out of the box. I usually wash y tanks when I'm done with the flavor that's in them, or for my ADVs maybe once a month, probably less... Yep, all metal parts from china come with an oily film to prevent corrosion during transit. So you need to wash them out of the box. I usually wash y tanks when I'm done with the flavor that's in them, or for my ADVs maybe once a month, probably less...