Rust Inhibitor on power cords/Xbox?

-Regarding the old XBOX GFCI powercords. Do any of you remember there being an oily film on the tip of the cord? I bought one from ebay and they told me Microsoft put it on there to prevent rust. However, I remember when they shipped one to me directly those many years ago, I don't remember there being an oily film on the power cord. In fact, I don't think I have ever seen a rust inhibitor on the tip of any cord? No?