Radium Engineering Catch Can Kit BMW E46 3-Series Fluid Lock - 20-0873-FL

The Radium Engineering Catch Can Kit for the BMW E46 3-Series (20-0873-FL) is a purpose-built oil catch can solution designed specifically for non-M3 E46 3-Series models. This kit intercepts crankcase vapors before they can deposit oil and moisture contamination inside your intake manifold, throttle body, and intercooler system — keeping your inlet air clean and your engine running the way it was designed to. What sets this kit apart from generic catch cans is Radium Engineering's patented Fluid Lock® technology, introduced in 2022, which adds a critical failsafe against reservoir overflow back into the intake tract.

Key Features & Benefits

• Patented Fluid Lock® System: A revolutionary internal mechanism prevents the reservoir from overfilling and traps collected fluids until you empty it — solving the long-standing risk of a neglected catch can dumping contaminated oil back into your air intake and degrading engine performance.
• 2-Step Oil Separation Baffling: Two stages of baffling inside the can more effectively separate oil mist and water condensation from crankcase gases before they can recirculate, delivering cleaner inlet air.
• Billet Aluminum Construction with Integrated Dipstick: The catch can is machined from billet aluminum and features an O-ring sealed integrated dipstick, making it easy to check the fluid level without disassembling anything.
• Laser-Cut, E46-Specific Mounting Bracket: The anodized aluminum mounting bracket is cut specifically for the E46 engine bay, mounting in the right-hand compartment near the firewall — no drilling required for a clean, factory-quality installation.
• Large 10AN Porting: Oversized 10AN ORB inlet and outlet ports minimize flow restriction for modified or higher-output engines, making this kit equally at home on a stock daily driver or a track-prepped E46.
• Closed System Design: By keeping crankcase vapors sealed and contained, the system prevents unwanted oil smells and contaminants from entering the cabin.
• Performance and Emissions Benefits: Cleaner inlet air can raise effective octane and support engine performance, while reducing hydrocarbon emissions — this product is SEMA certified 49-state legal.
• Everything Included for Installation: The kit ships with all necessary hardware so you won't need to source additional fittings or hose separately (see What's in the Box below).

Specifications

• Part Number: 20-0873-FL
• Catch Can Capacity: 7 fluid ounces
• Inlet / Outlet Ports: 10AN ORB
• Drain Port: 4AN ORB
• Baffling: 2-step oil separation
• Dipstick: Integrated, O-ring sealed
• Fluid Lock®: Patented overflow prevention mechanism
• Compliance: SEMA certified, 49-state legal

Fitment

This kit (20-0873-FL) is designed exclusively for BMW E46 3-Series non-M3 models, left-hand drive (LHD) only. The catch can mounts in the right-hand compartment of the E46 engine bay near the firewall, which means it is not compatible with right-hand drive (RHD) vehicles. Confirmed compatible model years and variants:

• 1998–2006 BMW E46 320i (LHD only)
• 1998–2000 BMW E46 323i (LHD only)
• 2001–2006 BMW E46 325i (LHD only)
• 1998–2000 BMW E46 328i (LHD only)
• 2000–2006 BMW E46 330i (LHD only)
• 2003–2006 BMW E46 330i ZHP (LHD only)

It is also compatible with early E46 models where the ABS module is mounted in the right-hand engine bay compartment. Note: If you own an E46 M3 or E46 M3 CSL, you need the separate 20-0073-FL kit, which is engineered specifically for that platform.

What's in the Box

• Billet aluminum oil catch can with integrated dipstick
• Laser-cut anodized E46-specific mounting bracket
• Anodized aluminum 10AN hose ends and adapter fittings
• Anodized aluminum V2 quick connect 10AN adapter fittings
• Enough 10AN (5/8") PCV hose to accommodate modified vehicles
• Stainless steel mounting hardware and hose clamps

Why Buy from ThreePiece.us

ThreePiece.us offers free shipping on every order, so the price you see is the price you pay — no surprise freight charges at checkout. Need to spread out the cost? Affirm financing is available, letting you get the parts you need now and pay over time. Our team has hands-on experience with performance fitment and is available to verify compatibility before you order — just reach out if you have any questions about whether this kit is right for your specific E46 build. We're here to make sure you get the correct part the first time.

Frequently Asked Questions

Does this kit fit my E46 M3?

No. The 20-0873-FL is engineered for E46 3-Series non-M3 models only. Radium Engineering makes a separate kit — the 20-0073-FL — specifically for the E46 M3 and E46 M3 CSL. Make sure you select the correct kit for your chassis.

Will this kit fit my right-hand drive E46?

No. The catch can mounts in the right-hand engine bay compartment near the firewall, and Radium Engineering specifies this kit for left-hand drive vehicles only. RHD E46 owners should not purchase this kit.

How often do I need to empty the catch can?

Collection rates vary from vehicle to vehicle. Radium Engineering recommends checking the level with the integrated dipstick starting at 3–4 weeks of driving and then repeating as needed to establish your own service interval. The patented Fluid Lock® mechanism adds a safety net against overflow if servicing is delayed, but the can should still be emptied regularly. If you notice excessive oil collection, it may indicate engine issues such as excessive blowby or a faulty PCV valve.

Do I need to drill any holes to install this kit?

No drilling is required. The laser-cut E46-specific mounting bracket is designed for direct fitment in the right-hand engine bay compartment, and the kit includes all necessary hardware, hose, fittings, and clamps for a complete installation.