A self-actuaring and pressure-activated hydraulic seal that optimizes cap seal performance. The cap seal design results in low breakout and running friction and minimal leakage over an extended service life, making this seal design ideal for dynamic service. The PTFE-type sealing element and advanced-design elastomeric energizer provide optimum radial squeeze and evenly distributed radial loading. The addition of circumferential cap grooves will improve the lubrication and reduce outboard leakage.