Methods and apparatus according to which a first valve is opened, or kept open, the first valve being part of a wellhead including a flow component above the first valve. The method may further include detecting a state of the first valve and, in response to detecting the state of the first valve, metering an amount of grease to the first valve. In addition, or instead, the method may further include opening, or keeping open, a second valve, the second valve being operably coupled to the wellhead and positioned above the flow component, and, after opening, or keeping open, each of the first and second valves, detecting whether the second valve is open or closed, in response to detecting that the second valve is open, preventing the first valve from being closed, and in response to detecting that the second valve is closed, allowing the first valve to be closed.