Best Air Oil Separator for Engines and Air Lines

#1 · Best Overall

1. K&N Air Oil Separator

• Weight: 2 lb

Best for: Factory-Hose Silverado and Sierra Owners.

Why it ranks #1: Vehicle-specific coverage lists several GM trucks and SUVs; the six-ounce reservoir, factory-style hose connections, and mounting bracket support a clear engine application.

A high-capacity 6-ounce reservoir gives the K&N Air Oil Separator a specific job: capture blowby oil before it reaches the engine and intake tract. Its listed applications cover select Silverado, Sierra, Suburban, Tahoe, and Yukon model years, making it a vehicle-specific option rather than a universal catch can.

The 6-ounce reservoir captures oil from engine blowby, helping protect the intake tract and reduce the risk of power loss or possible engine damage. Factory-style hose connections are intended to snap on and off, while the supplied mounting bracket supports installation; the product information estimates about 30 minutes for fitting. That combination suits owners who want a vehicle-specific setup with straightforward hose connections, provided their vehicle appears in the listed applications.

Skip it if you drive a vehicle outside its listed applications; the IAG Performance Universal Air/Oil Separator (AOS), Red, is listed for most engines.

This suits owners of the specified Silverado, Sierra, Suburban, Tahoe, or Yukon models seeking a bracket-mounted separator with factory-style hose connections. Check the listed vehicle years carefully; this is not the universal option in this group.

Listed on Amazon as: K&N Air Oil Separator compatible with 2014-2018 Silverado 1500, 2015-2020 Suburban, 2015-2020 Tahoe|2014-2018 GMC Sierra 1500, 2015-2019 Yukon|(See description for all applications) Catch Can, 81-0805

#2 · Best Subaru Fit

2. IAG Performance AOS for Subaru

• Weight: 10.5 lb

Best for: Specified-Year Subaru WRX and STI Owners.

Why it ranks #2: Designed for Subaru Impreza WRX 2006–2007 and STi 2004–2007, with an aluminum body, hose and fitting kit, and mounting bracket.

A supplied hose-and-fitting kit and mounting bracket make the IAG Performance AOS a vehicle-specific package for select Subaru Impreza WRX and STI years. Its stated purpose is to keep oil out of the intake tract, where oil can coat intake, intercooler, and piping surfaces.

The aluminum AOS targets oil in the intake tract, which the product information links to coating the intake, intercooler, and piping and potentially harming rubber or silicone hoses. Its hose-and-fitting kit and mounting bracket provide installation components in the package, while the listed vehicle applications narrow its intended fit to WRX 2006–2007 and STI 2004–2007. The 12-by-10.5-by-6-inch dimensions and 10.5-pound weight also matter when planning the engine-bay installation.

Skip it if you own a different engine or vehicle application; the IAG Performance Universal Air/Oil Separator (AOS), Red, is listed for most engine configurations.

This is for owners of the specified WRX and STI model years seeking an AOS with mounting and hose hardware included. Its vehicle-specific application is the key boundary; verify that your Subaru year falls within the listed range.

Listed on Amazon as: IAG Performance Air/Oil Separator (AOS) for Subaru Impreza WRX 06-07, STi 04-07 (Red)

#3 · Best Multi-Cylinder Fit

3. IAG Universal AOS

• Weight: 12.5 lb

Best for: Universal Multi-Cylinder Engine Builds.

Why it ranks #3: The universal kit is described for most engines with 4, 6, 8, 10, or 12 cylinders and includes quick-connect fittings and mounting brackets.

Compatibility with most engines from four through twelve cylinders makes the IAG Performance Universal AOS a broad-application option. Its quick-connect fittings and flexible aluminum mounting brackets support varied installation layouts, while the product information says separated oil does not require routine draining.

The kit’s SAE quick-connect fittings and universal aluminum brackets, with pre-drilled holes and suggested notches for bends or cuts, give installers options for adapting the mounting layout. Its stated coverage across most 4-, 6-, 8-, 10-, and 12-cylinder engines broadens potential use, though IAG says it cannot provide specific technical support or instructions for every engine model. The no-routine-draining maintenance claim may reduce upkeep compared with systems requiring routine draining.

Skip it if you need engine-specific installation instructions or support; IAG Performance IAG-ENG-7180RD lists specific Subaru WRX and STI applications.

This suits experienced installers seeking a broadly applicable AOS and flexible bracket mounting, especially where routine draining is unwelcome. The universal scope does not replace engine-specific guidance, which IAG says it cannot provide for every model.

Listed on Amazon as: IAG Performance Universal Air/Oil Separator (AOS), Red

#4 · Best Compressor Option

4. Vanair Spin-On Separator

• Weight: 4.6 lb

Best for: Spin-On Compressor-System Buyers.

Why it ranks #4: This spin-on separator is specifically described for compressor systems, where it removes oil from compressed air before it reaches downstream equipment.

A spin-on format distinguishes the Vanair 273080 Air/Oil Separator and gives compressor-system buyers a clearly named separator style to consider. Its stated function is to separate oil from compressed air, supporting cleaner air delivery where oil contamination could affect downstream equipment or end-use applications.

The Vanair separator removes oil droplets or mist from compressed air, a useful function where air quality matters to tools, pneumatic valves, instruments, or cylinders. Its spin-on designation identifies the format, while the listed 11-by-6-by-6-inch dimensions and 4.6-pound weight give buyers concrete figures for planning space and handling. The information describes a compressor-system component, but does not specify a particular compressor model or connection compatibility.

Skip it if you need a named compressor application or connection specification; Gardner Denver 202ECH6013 provides a specific model designation.

This fits buyers considering a spin-on separator for compressed-air applications where oil contamination can affect downstream equipment. Its dimensions help with space planning, but the supplied details do not identify compatible compressor models or connections.

Listed on Amazon as: Vanair 273080, Spin-On Air/Oil Separator

#5

5. Gardner Denver 202ECH6013

Best for: Gardner Denver Model-Specific Buyers.

Why it ranks #5: Its listed title identifies a Gardner Denver separator component, making it relevant to buyers matching a specific compressor part, though no fitment or dimensions are supplied.

The Gardner Denver 202ECH6013 name identifies this listing as a specific air/oil separator model, giving buyers a model designation to compare against their equipment requirements. The supplied product information names Industrial Service Solutions as the manufacturer, but provides no further application or construction details.

The listing identifies the product as Gardner Denver model 202ECH6013 and names Industrial Service Solutions as its manufacturer. That model designation gives a concrete reference for buyers comparing a required separator identifier with this item, while the manufacturer information helps distinguish it from other listings. No dimensions, connection details, compatibility information, or maintenance instructions are supplied here, so the available facts do not establish installation requirements or which compressor systems it suits.

Skip it if you need listed dimensions or connection specifications before selecting a separator; Vanair 273080 is listed with product dimensions.

This is for buyers who already recognize the Gardner Denver 202ECH6013 designation and need that named separator. The supplied details do not establish system compatibility, dimensions, connections, or service requirements, so those needs remain unresolved.

Listed on Amazon as: Gardner Denver 202ECH6013

#6

6. Boss Industries 304122 Separator

Best for: Boss Industries Model-Specific Buyers.

Why it ranks #6: The title identifies an air/oil separator by Boss Industries, but the supplied information gives no dimensions, system compatibility, or included installation components.

The Boss Industries 304122 designation is the clearest identifying feature of this air/oil separator, helping buyers compare the named model with an existing equipment requirement. Industrial Service Solutions is listed as the manufacturer; the supplied information does not provide further product specifications.

This listing names the product as a Boss Industries 304122 Air/Oil Separator and identifies Industrial Service Solutions as its manufacturer. The model designation provides a specific reference for buyers matching a required part description, rather than relying on a generic separator label. However, no dimensions, connection type, application range, materials, or maintenance details are supplied, so the available information cannot establish how it fits into a particular compressor installation or service routine.

Skip it if you need connection or application details to assess installation; Vanair 273080 includes product dimensions and a spin-on description.

This makes sense for a buyer seeking the specifically named Boss Industries 304122 separator. Because the listing supplies no dimensions, connection details, or application range, it cannot by itself confirm fit for a particular compressor system.

Listed on Amazon as: Boss Industries 304122 Air/Oil Separator

#7

7. Sullair 250034-112 Separator

• Weight: 5.92 lb

Best for: Sullair Model-Name Replacement Buyers.

Why it ranks #7: This is explicitly an air/oil separator, with package dimensions of 11.34 by 10.2 by 9.92 inches; system compatibility is not specified.

The Sullair 250034-112 model designation gives buyers a specific air/oil separator identity to compare with an existing equipment requirement. Industrial Service Solutions is listed as the manufacturer, and the supplied package dimensions and weight provide limited handling and storage information.

The product title identifies this as a Sullair 250034-112 Air/Oil Separator, with Industrial Service Solutions named as manufacturer. Package dimensions are listed as 11.34 by 10.2 by 9.92 inches, and package weight is 5.92 pounds; these figures can help with receiving, storage, or handling plans. The supplied information does not give connection details, application range, or maintenance guidance, so it does not establish compatibility with a particular compressor system.

Skip it if you need connection specifications to establish compressor fit; Vanair 273080 at least identifies a spin-on separator format.

This is for buyers seeking the specifically named Sullair 250034-112 separator and using package measurements for handling or storage. The supplied listing does not establish application or connection compatibility for a particular compressor.

Listed on Amazon as: Sullair 250034-112 Air/Oil Separator

#8 · Highest Capacity

8. EVIL ENERGY 10AN Catch Can

• Weight: 2.81 lb

Best for: High-Capacity Performance Engine Setups.

Why it ranks #8: Its 1.2-liter capacity and dual breather filters suit buyers seeking a larger universal catch-can setup, but confirm its 10AN and M22 adapter fit.

A 1.2-liter capacity is the defining feature of this EVIL ENERGY catch can, giving high-displacement or performance-engine setups more stated volume for oil particles and moisture. Two breather filters and 10AN ports with M22 x 1.75 adapters further specify its ventilation and connection arrangement.

The 1.2-liter reservoir is described as holding more oil particles and moisture, with the product linking that capacity to reduced cleaning frequency. Two breather filters are intended to maximize ventilation and relieve crankcase pressure, while 10AN inlet and outlet ports use M22 x 1.75 fitting adapters. The aluminum construction is another listed material detail. Together, these specifications make capacity and port compatibility central checks when planning the installation.

Skip it if you need a smaller 300-milliliter setup with 3/8-inch hose; EVIL ENERGY KT01300BK-AMZ1 lists that capacity and hose size.

This suits high-displacement or performance-engine owners who value a larger stated reservoir and dual breather filters. Confirm that the 10AN ports and M22 x 1.75 adapters suit the intended plumbing before choosing this configuration.

Listed on Amazon as: EVIL ENERGY 10AN Oil Catch Can 1.2L – Dual Breather Filter, Universal Baffled Catch Can Kit Aluminum Air Oil Separator with Drain Valve

#9

9. EVIL ENERGY 300ml Catch Can

• Weight: 0.91 kg

Best for: Custom 3/8-Inch Hose Setups.

Why it ranks #9: This baffled universal catch can includes a 300 ml aluminum can, 3/8-inch hose, adapters, clamps, and bracket; its hose size needs verification.

A 300-milliliter capacity and included breather filter define the EVIL ENERGY catch-can kit for custom setups. It is universal rather than vehicle-specific, and its supplied 3/8-inch hose and M161.5 inlet and outlet threads give buyers concrete sizing details to check before installation.

The aluminum can holds 300 milliliters, while the kit includes a 3/8-inch-ID NBR fuel hose, six adapters, two hose clamps, steel wool, a bracket, and an installation guide. Those included parts give a custom installer several listed fitting components, but the product explicitly advises measuring the original hose inner diameter, confirming fittings, and checking mounting space. That measurement step matters because this kit is not vehicle-specific.

Skip it if you want a listed vehicle-specific application rather than a universal kit; K&N 81-0805 names Silverado, Sierra, Suburban, Tahoe, and Yukon applications.

This suits custom automotive installations where the owner can measure hose size, confirm fittings, and assess mounting space. The 300-milliliter capacity and supplied hardware are useful, but it does not identify a vehicle-specific fit.

Listed on Amazon as: EVIL ENERGY Oil Catch Can, 300ml Baffled Catch Can Kit with Breather Filter

#10

10. NEIKO 30253A Air-Line Separator

• Weight: 0.16 kg

Best for: Compact Air-Tool Line Users.

Why it ranks #10: This compact 1/4-inch NPT unit filters water and oil for air tools and paint guns at 25–150 PSI, not engine crankcase ventilation.

A universal 1/4-inch NPT inlet and outlet make the NEIKO 30253A a compact choice for air lines serving tools or paint spray guns. Its water-and-oil separation, with a stated operating range of 25 to 150 PSI, addresses common contaminants in pneumatic equipment workflows.

The aluminum separator uses solid brass fittings and universal 1/4-inch NPT inlet and outlet connections, giving air-tool and paint-spray-gun users a defined line interface. Its 25-to-150-PSI operating range provides a pressure boundary for matching it to a setup. The product information also says it filters particles, dust, dirt, debris, water, and oil, helping protect downstream pneumatic tools; its compact form suits an air-line accessory role.

Skip it if you need a separator rated above 150 PSI; Vanair 273080 is a compressor-system spin-on separator with no pressure rating supplied here.

This suits users fitting a 1/4-inch NPT air line for pneumatic tools or paint spray guns within the stated 25-to-150-PSI range. Check the line connection and operating pressure against those limits.

Listed on Amazon as: NEIKO 30253A Water and Oil Separator for Air Line | 1/4" NPT Inlet and Outlet | 150 PSI | Air Compressor and Air Tool Accessory | Protect Lifespan of Pneumatic Tools | Optimize Performance, Black