Upgrade Your B58 Catch Can System with a True Dual-Vent Solution

Take your B58 BMW or Supra’s crankcase ventilation performance to the next level with the BMS Oil Filler Cap Dual Vent Connection Kit = the missing link for ultimate catch can and engine efficiency. 

This precision-machined billet cap replaces the factory oil filler cap and creates a second dedicated exit point for dirty PCV gases. That means both the crankcase vent and the valve cover breather can now be routed into your oil catch can. Twice the inputs into your catch can means twice the oil vapor capture, keeping harmful oil mist out of your intake tract. Cleaner air, cleaner intake valves, and a more efficient PCV system, more efficient engine, it’s a simple upgrade with major payoffs. 

Why This Matters:

• Double the Captured Flow: Adds a second breather port for PCV/vapor extraction so you pull more blow-by gasses into your catch can.
  
  
• Reduces Piston Resistance: This creates a slight negative pressure (vacuum) in the crankcase, reducing the resistance the pistons face as they move, improving fuel economy and performance.
  
  
• Manages Pressure: "Blow-by" gases (unburned fuel, air, combustion byproducts) get past piston rings into the crankcase, creating pressure.
  
  
• Cleaner Combustion Air: Reduces oil vapor recirculation that leads to intake valve carbon buildup. 
  
  
• Maximized Catch Can Efficiency: Works with the BMS catch can to let it do more of its job. 
  
  
• Perfect For: Anyone running a B58 BMS oil catch can looking to squeeze every bit of performance and protection from their PCV system, especially on tuned or high-boost builds.
  
  

• Precision-Built Fit: CNC billet aluminum construction replaces the factory filler cap for a secure, purposeful connection. 

• All Hardware Included: Includes billet cap, AN fittings, high-temp hose, T-fitting, and clamps for a clean install. 

Vehicle Fitment
Gen 2 B58-powered BMW and Supra and Gen 3 B58-powered BMW

For use with 

BMS Oil Catch Can for G Chassis Gen 2 B58 BMW M240 M340 M440

BMS Oil Catch Can for 2020+ B58 Toyota Supra GR MK5

BMS Oil Catch Can for G Chassis Gen 3 2025+ B58 BMW M340 M440

B58 Vehicle Fitment

BMW 2 Series
• 2022+ G42 B58 BMW M240i

BMW 3 Series
• 2019+ G20 G21 B58 BMW M340i

BMW 4 Series
• 2021+ G22 G23 G26 B58 BMW M440i

Toyota
• 2020-2026 Toyota GR Supra Mk5 B58

What's Included:
(1) BMS B58 BMW Billet Oil Filler Breather Cap 
(1)-12ORB 90º to -12AN fitting
(1)-12 AN barbed straight Fitting
(1) Heavy-duty custom silicone hose
(1) Barbed PCV T- fitting
(3) Hose clamps

⚠️ ATTENTION: This installs differently than the OEM oil filler cap. To install, line the grooves up with the tabs on the filler neck on the car, push all the way down and twist down tightly. Be sure they cap is seated and tightly sealed before use to prevent leaks.