FA-3539 High-Flow Washable Air Filter – Replaces OEM 3539-Style Air Filters

$769.00

Full Long Description (Mechanic Authority)

After decades working on heavy-duty diesel engines, I’ve learned that intake restriction almost never shows up as a sudden failure. It shows up as higher EGTs, lazy throttle response, excess soot, and DPF systems that regen more than they should. OEM 3539 paper filters do their job when they’re new, but once they load with dirt, restriction climbs fast.

That’s why I designed the FA-3539.

This is a high-flow, washable air filter, engineered to maintain airflow over time instead of choking the intake as miles stack up. The synthetic filter media resists collapse and airflow drop-off under sustained load, keeping the turbo operating in its efficiency range and combustion stable.

Sealing matters just as much as airflow. The FA-3539 uses OEM-matched sealing geometry so air goes through the filter — not around it. No bypass means better protection for the turbo, charge-air cooler, and engine internals.

Instead of throwing away paper filters every service interval, you wash the FA-3539, oil it correctly, reinstall it, and keep running. One filter replaces years of disposable elements, reduces downtime, and lowers long-term operating cost without sacrificing engine protection.

Compatibility Note:
If your truck or equipment calls for an OEM 3539-style air filter, the FA-3539 is a direct drop-in replacement with no modifications required.

4. Replaces OEM & Aftermarket Filters (Table Format)

Brand / Category	Filter Part Number or Type Replaced
OEM	3539 Air Filters
OEM / Aftermarket	3539-Style Paper Filters
Aftermarket	Equivalent 3539-Series Intake Filters
Fleet / Fleetguard	3539 Equivalent Filters
Baldwin	3539 Equivalent Filters
Donaldson	3539 Equivalent Filters
Wix / NAPA	3539 Equivalent Filters

Note: Replacement compatibility is based on factory 3539 dimensions and sealing geometry. Exact brand part numbers may vary by catalog.

5. OEM Cross-Reference Table

OEM / Factory Part #	Application Type	Replaced By
3539	Heavy-Duty Diesel Intake	FA-3539
3539-Style Paper Filter	Class 6–8 Diesel	FA-3539

6. Features & Benefits

Features

High-flow washable synthetic filter media
OEM-matched sealing flange
Designed for turbocharged diesel airflow
Reusable, serviceable construction
Drop-in replacement for 3539-style filters
Built for high-mileage and fleet use

Benefits

Maintains consistent airflow under load
Reduces intake restriction over time
Helps reduce forced DPF regens
Lower exhaust gas temperatures
Improved throttle response
Less downtime from filter replacements
Long-term savings vs disposable paper filters

7. Competitor Differentiation (Mechanic Truth)

Disposable paper filters are designed to be replaced, not to maintain airflow. As they load with dirt, restriction climbs and performance drops.

I built the FA-3539 to hold airflow steady over time, not just look good when it’s clean. Washable media keeps restriction lower, sealing surfaces actually seal, and the filter doesn’t become trash after one dirty service cycle.

Disposable filters keep you buying. A properly engineered washable filter keeps your engine breathing right and your operating costs under control.

Made in the USA!

A set of two Fleet Air Filters

*Price does not include Klotz Oil*

Fits:

Freightliner: Classic

Kenworth: T800, W900LL

Peterbilt: 367, 377, 387, 388

Western Star

If your filter number or truck is not listed please call us at 251.654.0892!