Written with people moving from Turkey in mind. The Portuguese rules still apply more broadly.
Gas Station Etiquette
In Portugal, you usually pump your own gas first and pay inside afterwards. However, at night (after 22:00) or on highways, many pumps require pre-payment (Pré-Pagamento) at the counter or via an automated terminal.
Never leave your car parked at the pump after filling up to go do extensive shopping inside. Move your car to a parking spot first. "Gasóleo" is Diesel (black/yellow handle), and "Gasolina 95" is Unleaded (green handle).