Disclosed is a supply device for supplying a consumer with a viscous medium, in particular a lubricant supply device, including at least a reservoir for the viscous medium including a follower piston which includes a ring seal at its circumferential edges and is supported on the viscous medium and which separates the reservoir into a space supplied with a viscous medium and an air space, and a feed pump for feeding the viscous medium from the reservoir to a medium outlet, such that further in the reservoir at least one opening is provided which serves to receive a ventilation apparatus via which the reservoir is in air-exchanging contact with the exterior surroundings, such that the opening is arranged in the reservoir such that in a determined filling state of the reservoir the ring seal at least partially overrides the opening so that the space supplied with a viscous medium is in fluidic connection with the opening.