The oil quantity is checked during our cockpit setup before each flight. It is also displayed while we start the engines and it must be at least 70% before we initiate each engine start. You need a ladder to reach it. The ramp workers would tell us it is open. We'd call to have the fueler return to close it. They'd also have to make sure that the panel's controls were properly configured after fueling was completed. On the 737, the fueling panel has a fuel gauge for each of the three tanks, a fill-valve switch for each tank, a fill-valve position light for each fill-valve, and a three-position indicator test switch. The fueler must understand the fuel loading schedule and manually direct the correct amount of fuel into each of the fuel tanks. Yes, but we'd shut down the engine. We start the Number 2 engine first, which is near where the fuel panel is located. We'd shut that engine down to allow the fueler to safely access the panel. Here's a picture of a 737 refueling panel.