I've got two tubes of oil paint...Lamp Black and Yellow Ocher...that I've never opened or used along with a can of Odorless Thinner. When I was researching various weathering methods, I picked them up along with various other materials and just never gor around to trying them. I picked mine up at Hobby Lobby for something like $3 a tube and they had a nice selection to choose from.
The fact that I use enamels exclusively has made me wary of the oils and I like the results I'm able to achieve via other methods, so there they sit. [:D}