One thing though, they all mentioned that they're all having headaches with the weekly price revisions as all their stocks are controlled by the petrol companies - sometimes, they just know when:

Fuel price will decrease when fuel tankers will line up to fill up their tanks at optimal / full levels on Tuesday and Wednesday
Fuel price will increase, when fuel tankers will generally not come on Tuesday and Wednesday, and their station tanks remain low - fuel tankers will come on Thursday