If anyone has bought a used part or junkyard part, they use a yellow or some color marker that they write on the part itself.

1) why do they do this? (is it to show that its a used part to mechanics, potential future buyers, or just there way of inventory system)

2) what kind of marker is it? (i ask this because almost nothing can remove it, its like a highlighter on steroids)

3) and finally how do you remove it. It would look bad to pop ur hood and have some yellow part number or whatever written on it.

I am just curious, i dont have any used parts but was just thinking about it when i helped my friend get some for his car.

I tried to remove it on a peice of rubber/plastic part and i tried EVERYTHING and i told him he would have to live with it, lol.