A common carrier, contract carrier, manufacturer, refiner, special fuel seller, wholesaler of motor fuel, or person who buys motor fuel in bulk for resale in bulk who is engaged in the transportation of motor fuel may not willfully adulterate or commingle: gasoline with special fuel; or gasoline by brand or grade. Except for motor fuel intended for its own use, a petroleum transporter may not place an additive in motor fuel. This section does not prohibit the adulteration or commingling of gasoline that occurs as a result of transit through a pipeline system.