A hero with merchant skill trades goods to earn money for you. Each tick the hero has 2 chances (equal to the merchant skill) to trade his good for a better one. After 6 hours he gives it to you and you can sell it. Each hero can store at most 6 goods.
So after 3/12 ticks the merch's max should be oil. Yet one of my heroes managed to get Salt. So either tick counter is off or something is wrong with merch skill
