A closure cap for the filler neck of a reservoir, in particular, one for fuel or motor oil for e.g. motor vehicles, comprising a grip and a rotating lifting device whose first part (sealing part) facing the grip is provided with a sealing ring and whose other part (tightening part), which faces away from the grip and which is provided with detent lugs serving to engage under a closure cap of the filler neck, can be turned relative to the filler neck when the closure cap undergoes a turning motion. The other part (tightening part) can, when the grip undergoes a turning motion, be axially displaced relative to the first part (sealing part) of the rotating lifting device against the force of a spring. This axial displacement is such that, in the closed position of the closure cap on the filler neck of the sealing ring provided on the first part (sealing part), the tightening part is pressed against a sealing surface of the filler neck, and during the movement of the grip, an axial play exists between the sealing surfaces of the sealing ring and filler neck, whereby the first part (sealing part), with the axially acting sealing ring remains, when the closure cap undergoes a turning motion relative to the filler neck, unturnable with the filler neck by means of a turning closing connection.