There is a 0% sell tax & buy tax.
The token starts with an initial supply of X $OIL, repartitions is as follows :
$cOIL is the second currency of Petroleum. This currency is issued as reward and have to be refined before to become $OIL. With $cOIL you can buy any items, repair your Reward Items, buy a Refinery & more.
$cOIL allow you to compound your rewards without any taxes cause there is no claim fees on it.
$cOIL is an in-game currency and is not for sale. You have to refine it before to get $OIL that you will be able to sell.
The Initial supply of cOIL will be sold at the Presale, and used for Airdrops
To understand the rewards mechanics & the utility of each item check :