Most gas station credit cards require applicants to have an established credit. Sunoco credit card is issued by Citi which means that approval requirements will be strict and you may not qualify for this card without any credit history at all. Since your goal is to build your own credit, we would recommend you to apply for a general credit card. This will help you avoid unnecessary credit card use and will help you to concentrate on credit building. Also, general credit cards often come with credit and score trackers that make credit monitoring easy.