PRL Catch Can vs AOS: Which Oil Separator for Your Honda
By PRL Motorsports - Premium Automotive Performance Products | Published: 2026-10-18
Category: Comparisons
Compare catch can and AOS oil separators for turbo Hondas. Learn which setup suits your L15B7 or K20C1 engine based on maintenance, performance, and budget.
Quick answer
For most turbo Hondas, a catch can offers better oil separation and easier maintenance, while an AOS (Air Oil Separator) provides a cleaner, more automated setup. If you track your car and want to manually inspect collected oil, go with a catch can. If you prefer a set-and-forget solution that returns oil to the pan, choose an AOS.
How Catch Cans and AOS Work
Both catch cans and AOS units prevent oil vapor from recirculating into your intake, which can cause carbon buildup and detonation on direct-injection turbo engines like the L15B7 and K20C1. A catch can traps oil in a reservoir you empty manually. An AOS separates oil and returns it to the oil pan, so you never have to drain it. The tradeoff is that catch cans give you a direct view of blow-by volume, while AOS systems are more integrated but can be harder to diagnose if something goes wrong.
Key Differences for Turbo Honda Owners
On a daily-driven L15B7 Civic Si, a catch can is a simple, affordable upgrade that catches oil before it reaches the intake valves. For a track-focused K20C1 Civic Type R, an AOS may be preferable because it continuously returns oil, reducing the chance of oil starvation during high-G cornering. However, an AOS typically costs more and requires more complex plumbing. Both options are effective, but your choice depends on how much maintenance you want and whether you prioritize track performance or street convenience.
Installation and Maintenance Considerations
Catch cans are generally easier to install and require periodic emptying—every 1,000 to 3,000 miles depending on driving conditions. AOS units involve tapping into the oil pan or valve cover, which can be more involved but eliminates the need to check a can. If you live in a cold climate, an AOS may also help prevent freezing because it keeps oil circulating. For most street-driven turbo Hondas, a quality catch can like those from PRL Motorsports offers the best balance of cost and effectiveness.
Catch Can vs AOS Tradeoffs
- Maintenance: Catch cans need periodic emptying; AOS units return oil automatically. Choose a catch can if you want to monitor blow-by; choose AOS for convenience.
- Cost: Catch cans are generally less expensive than AOS systems. If budget is tight, a catch can gives you effective oil separation for less money.
- Track vs Street: AOS systems reduce oil starvation risk during high-G cornering; catch cans are simpler for daily driving. Track-focused builds benefit from an AOS; street cars do well with a catch can.
Products That Complement Your Oil Separator Setup
- Honda K24Z Oil Filter Housing Block-Off Plate Kit: The Honda K24Z Oil Filter Housing Block-Off Plate Kit is required when swapping to the Acura RSX Type-S PRB oil pump to eliminate balance shafts and improve oil supply at high RPM. If you're building a high-revving K24Z engine, this kit ensures your oil system can keep up with the demands of a catch can or AOS setup.
- 2022+ Honda Civic 2.0L Replacement Panel Air Filter Upgrade: The 2022+ Honda Civic 2.0L Replacement Panel Air Filter Upgrade is a drop-in filter that requires no ECU calibration and improves airflow. Pairing a high-flow air filter with an oil separator helps your turbo engine breathe better while keeping the intake clean from oil vapor.
Which Oil Separator Fits Your Build?
Best for
- Daily-driven L15B7 or K20C1 owners who want a simple, affordable upgrade
- Enthusiasts who enjoy checking and emptying their catch can regularly
Not for
- Track-focused builds where oil starvation is a concern (consider an AOS instead)
- Drivers who prefer a maintenance-free solution (choose an AOS)
