Oil catch cans are one of the most misunderstood yet essential modifications in the automotive world. While their primary function is to prevent crankcase oil vapours from re-entering the intake system, a properly installed catch can also reduces carbon build-up, improves engine longevity, and optimises performance—especially in forced induction and high-revving applications.
But here’s the thing—installing a catch can isn’t always straightforward. There’s no universal, plug-and-play solution, as different engines have different PCV systems, boost levels, and oiling characteristics. This guide will deep dive into the correct installation methods, common mistakes, and how to adapt a catch can system to suit your setup.
If you’re looking for a shortcut or a generic guide, this isn’t it. But if you want to set up a catch can properly, avoid oil starvation or CELs, and get the best long-term results, this is the most detailed resource you’ll find.
How the PCV System Works (and Why It’s Flawed)
Before we get into installation, let's clear up some common misconceptions about PCV systems and why an oil catch can is necessary.
The Positive Crankcase Ventilation (PCV) system was designed to vent excess crankcase gases back into the intake manifold instead of venting them to the atmosphere. While this helps with emissions compliance, it’s a performance disaster for many engines.
Problems with Stock PCV Systems
- Oil Contamination in the Intake – Over time, excess oil vapour from the PCV system coats the intake manifold, throttle body, intercooler, and valves, leading to carbon build-up and reduced airflow.
- Knock and Pre-Ignition – Oil mist in the combustion chamber lowers octane levels, increasing the risk of detonation in high-compression or forced induction engines.
- Excessive Blow-By – As engines wear, piston ring sealing deteriorates, leading to more oil vapour and pressure build-up in the crankcase.
- PCV Systems Are Not Designed for Boost – On turbocharged or supercharged setups, PCV valves often fail under boost, allowing unmetered air to enter the intake and throwing off fuel trims.
A well-installed oil catch can system prevents these issues by separating oil mist from crankcase vapours, allowing only clean air to re-enter the intake.
Single vs. Dual Catch Can Systems: What’s Best for Your Setup?
Your engine’s PCV system design, power level, and use case will determine whether you need a single or dual catch can setup.
Single Catch Can Setup (PCV Only) – Best for Street & NA Builds
- Route: PCV valve → Catch can → Intake manifold
- Works Well For: Naturally aspirated engines or mild boost setups
- Benefit: Stops oil mist from being pulled into the intake during vacuum conditions
- Potential Issue: Doesn’t capture crankcase vapours under high load
Dual Catch Can Setup (PCV + Crankcase Vent) – Best for Forced Induction
- Route 1: PCV valve → Catch can → Intake manifold
- Route 2: Crankcase breather → Catch can → Intake pre-turbo (or vent to atmosphere)
- Works Well For: Turbocharged, supercharged, and high-RPM engines
- Benefit: Captures oil mist in both vacuum and boost conditions
- Potential Issue: Requires more space and careful routing
For high-horsepower turbocharged builds, a vent-to-atmosphere (VTA) system with a check valve might be necessary to prevent backpressure issues.
Where to Mount Your Catch Can
Correct placement is critical for effectiveness.
- Mount it HIGH in the engine bay – Oil is heavy; gravity helps drain it into the can.
- Avoid excessive heat – Don’t place it too close to the exhaust manifold or turbo.
- Secure it properly – Use solid mounts to prevent vibrations from loosening fittings.
Choosing the Right Fittings & Hoses
Hose routing makes or breaks a catch can system. Using the wrong fittings or lines can lead to poor separation, vacuum leaks, or even oil starvation.
Hose Selection
✅ AN-style PTFE hoses – Ideal for high-temp, oil-resistant applications
✅ Reinforced rubber fuel/oil hoses – Good for street setups
❌ Standard vacuum hoses – Will degrade over time
Fitting Types & Considerations
- Push-lock fittings are fine for low-boost applications but can leak under high pressure.
- AN fittings provide a secure, leak-free connection.
- Baffled catch cans improve separation efficiency and reduce oil mist bypass.
Troubleshooting Common Catch Can Issues
Even experienced mechanics can run into problems if the installation isn’t perfect. Here’s how to diagnose and fix common issues.
1. Why is my catch can filling up too fast?
Possible causes:
✅ Excessive blow-by – Engine may be worn or running too rich
✅ Poor baffling in catch can – Upgrade to a baffled catch can for better separation
2. My catch can is bone dry. Is it even working?
Possible causes:
✅ Incorrect routing – Check that vapours are actually flowing through the can
✅ PCV valve malfunction – Some engines have PCV valves that close under boost, preventing oil mist from reaching the can
3. Will a catch can trigger a CEL?
Possible causes:
✅ Some modern PCV systems monitor pressure drop; ensure your can doesn’t restrict airflow excessively
✅ Some catch cans require a check valve to prevent pressure imbalances
Maintaining Your Catch Can: What You Need to Know
Even the best catch can won’t work forever without maintenance. Here’s how to keep yours functioning optimally.
Emptying Schedule:
- Daily driven street cars: Every 3,000–5,000km
- Track cars: Check after every event
- Cold climates: Empty more often, as condensation can increase volume
Cleaning:
- Flush with brake cleaner or degreaser every oil change.
- Inspect for clogged hoses or filters.
Final Thoughts: Need Help?
If you’ve followed this guide, you should have a rock-solid catch can setup that maximises performance, reduces carbon build-up, and extends engine life.
However, every engine is different—so if you're still unsure where to mount your catch can or how to route it for your specific setup… Please send us a message via the chat icon at the bottom right of our website with a photo of the engine bay.
Our team will review your setup and point you in the right direction to ensure you get the best results without guesswork.