1st rule of buying oil, don't trust who you buy from. 2nd rule of buying oil, don't trust who you buy from .first time weve ever bought it, lesson learned (repeating theme lol)
Oil companies work on a margin above cost price and the sales people aim to increase that margin every time they sell to you. The more loyal you are, the bigger price you pay. Awful but true. Ring 3 companies, don't be afraid to play one off against the other, in fact actively do that.
3rd rule of buying oil, do what GB72 said about buying in August. Fill to the brim then