Description
The Precision Works Oil Control Valve is a high-performance solution engineered to address one of the most common weaknesses of the Subaru EJ25 boxer engine—oil surge in the cylinder heads during aggressive driving and hard cornering. Designed, machined, and assembled in-house using advanced Haas 5-axis CNC equipment, this component delivers precision fitment, durability, and proven performance for both street and track use.
Under high lateral G-forces, oil can be forced into the valve cover ports, overwhelming standard PCV systems, air/oil separators, and catch cans. This condition can cause rapid oil loss, increased risk of oil starvation, and in severe cases, oil overflow onto hot engine components. The Precision Works Oil Control Valve prevents this by intelligently managing oil flow at the cylinder head ports.
Inspired by a design long used in aerobatic aircraft, the valve automatically blocks oil from exiting the affected head port during extreme cornering while still allowing proper crankcase ventilation during normal driving, acceleration, and braking. Only the port experiencing oil surge is closed, while all other ports remain fully operational. This ensures consistent blow-by evacuation with no negative impact on engine performance or drivability.
Vehicle Fitment
• Subaru WRX 2008–2014
• Subaru WRX STi 2008–2014
The result is a cleaner, safer, and more reliable oil management solution, making this Oil Control Valve an essential upgrade for Subaru WRX and STi owners who demand maximum protection and performance during spirited driving or track events.
