A supplier is the party that sells fuel into the distribution chain. It may be a refiner that makes the fuel or a company that owns fuel sitting at a terminal.
The supplier is the source a jobber buys from. Sometimes that is a refiner, the company that turns crude oil into gasoline and diesel. Other times it is a company that does not refine anything but owns fuel held at a terminal (the large storage and loading hub fed by pipeline or barge) and sells it on from there.
A jobber signs a supply contract with a supplier to keep its trucks full. That contract sets the price formula, how much fuel the jobber can lift, the credit terms, and whether the fuel is branded or unbranded. The supplier is the other name on that deal.
The words supplier, jobber, and distributor get blurred together, but they sit at different points. The supplier sells fuel into the chain, the jobber buys it and hauls it out to local accounts, and a distributor is another word for that reselling middle role. Knowing who is the supplier in a given deal tells you who owns the fuel and who carries the price.
In useThe jobber lines up a reliable supplier first, because a contract to deliver fuel means nothing if you cannot count on buying it.
See also Jobber, Supply contract, Terminal