Abstract: An improved seal for use in a hydraulic system such as a piston rod in a housing, the seal having a stressing member and sealing member in which the latter is in point contact with, for example, a piston rod under low fluid pressure and has an additional contact area with the piston rod under high fluid pressure; a shallow concavity between the point contact and the contact area entraps lubricating fluid when the seal is subjected to high fluid pressure. In another modification the sealing member has an incline on the face in contact with the stressing member so that under high fluid pressure, the stressing member is forced up the incline and thus exerts increased pressure through the sealing member against the contact area and produces an effective high fluid pressure seal. In still another embodiment the sealing member has a concave surface to receive the stressing member such that it is centered, during low pressure operation, over a sealing contact area of the sealing member.