Harley Benton Feeler Gauges

The feeler gauges arrived completely covered in an oil with a strong smell of petroleum. The oil had leaked inside the soft plastic cover, which is now unusable, and had even leaked onto the other items I ordered, to the point that they now have that same awful smell of petroleum.
When I tried to rinse the feeler gauges (only way to be able to use them), they quickly oxidised and turned black. They do not stink anymore, but now they leave black oxide marks when you touch them.
I probably won't be able to use the item, and most certainly not onto a guitar !!