This necklace contains black crystals caged in the rings used in its making, this is where the allusion of oil stains comes from.
In fact, even if you really stain it with oil, since it is made with stainless steel, a little soap and water will recover it's original shine.
On the other hand, to get rid of the stains in black crystal, you'll have a little more difficulty!!
Then don't be afraid to wear it during your oil change, it will bring you lots of comments from the people around!