A flow restrictor (1) for use in bearing formation between a piston (2) and a cylinder (3) of a gas compressor (4). The gas compressor (4) includes a protective pad (5) that externally surrounds the cylinder (3), and an inner cavity (6) is disposed between the protective pad (5) and the cylinder (3), fluidly fed by a discharge flow from a compression movement exerted by the piston (2). The gas compressor (4) further includes a bearing formation gap (7) that separates an outer wall of the piston (2) and an inner wall of the cylinder (3). A flow restrictor (1) is provided with a housing (12) that fluidly associates the inner cavity (6) to the bearing formation gap (7). The flow restrictor (1) includes a limiting tube (8) associated with the housing (12), provided with at least one restraining portion provided with a cross section sized to limit the gas flow from the inner cavity (6) to the bearing formation gap (7).