If you've upgraded to a reusable K&N air filter, you've made a great long-term investment in your vehicle's performance and efficiency. However, these filters require routine service to perform correctly—you can't just toss them like a paper filter.
We’re showing you how easy it is to clean and re-oil your K&N filter, returning it to brand-new condition. We walk through the process on our own 3.5L EcoBoost engine, a service that takes less than an hour of actual work time and saves you money on replacement filters.
Why Clean Your K&N Filter?
The K&N filter uses oiled cotton gauze to trap contaminants. Over time, that oil becomes saturated with dirt, debris, and sand (especially for vehicles in dusty climates, like our Arizona-sourced Ford Explorer). A dirty filter chokes your engine's airflow, hurting performance and fuel economy.
Cleaning it is not just maintenance; it’s essential to ensure your EcoBoost engine is breathing easy.
Step-by-Step K&N Filter Cleaning Guide
You will need a K&N Filter Cleaning Kit, which includes the special cleaning solution and the red filter oil.
1. Filter Removal
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Access: Open your hood and locate the airbox. On the 3.5L EcoBoost, you will need to undo the plastic clips or loosen the cover (depending on your intake setup) to lift the filter out of its tray.
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Inspection: Take note of how dirty the filter is. If you're flipping a car and found one of these installed, it's always a good idea to perform this service.
2. Cleaning and Rinsing
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Spray the Cleaner: Liberally spray the K&N Filter Cleaner onto both sides of the filter. Make sure the filter is saturated to lift all the grime, dirt, and trapped bugs.
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Soak: Let the cleaner soak for about 10 minutes. Do not let the cleaner dry on the filter.
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Rinse: Using low-pressure water (like a garden hose or a low-flow faucet), rinse the filter from the clean side out. This forces the dirt out of the filter, instead of pushing it deeper into the cotton fibers. Continue rinsing until all the foam and dirt are gone.
Rinsing Tip: You want to spray from the clean side (the side facing the engine) to the dirty side (the side facing the outside air). See the full video demonstration for the proper rinsing angle.
3. Drying and Re-Oiling
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Dry Time: Shake off any excess water and allow the filter to air dry for 10–15 minutes. Never use compressed air or a heat gun, as this can damage the cotton fibers.
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Re-Oil: Once completely dry, apply the K&N filter oil. Spray a thin, even coat of oil onto the filter. Start with the top, let it sit for a few minutes to soak in, then flip it over and spray the bottom. The goal is to see the signature pink/red color evenly coat the entire filter.
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Reinstall: Once the oil is dry and the filter is evenly coated, place it back into your airbox.
Save Money and Stay in Tune
While a K&N filter costs more up front, its reusability saves you money on paper filters in the long run and prevents waste.
Routine maintenance is the key to keeping any EcoBoost engine running smoothly. If you're tackling maintenance yourself, you need to be prepared:
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Deeper Engine Maintenance: For more essential 3.5L EcoBoost tips, check our guide on The Top 3 EcoBoost Timing Chain Mistakes You MUST Avoid!.
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Proper Vehicle Support: When performing any work under your vehicle, ensure you know your lift points! See our guide on Stop Crushing Your Frame! The Exact Ford Explorer Jack Points.
Since proper maintenance often includes checking for hidden issues, having a reliable diagnostic tool is non-negotiable.
We highly recommend having an affordable diagnostic tool on hand for all your repair and maintenance needs.
Click here to buy an affordable scanner and other Diagnostic Tools! https://sellthoseflippingcars.com/store/diagnostic-tools
Watch the full video guide: K and N Air Filter Service Made Easy – DIY Cleaning Guide