The invention is based on the insight that a filling system obtained by combining a “Kruse” compatible threaded socket and an annular magnet as required for the operation of the “Elaflex” nozzle, will exhibit air exchange problems related to the difference in the positioning of the respective air intake openings of the “Kruse” bottle and the “Elaflex” nozzle. More particularly, the invention is based on the insight that by judiciously providing a chamber in fluid communication with the volume of air or vapor in the tank, filling may be made possible with a “Kruse” bottle as well as with an “Elaflex” nozzle.