How to really get your K&N air filter really, really clean

Out there on the sinterweb, there’s a lot, a hell of a lot – maybe even too much, but there are also some gems. I’ve yet to find a really good technique for cleaning out K&N filters – well I’ve not found one, yet…. So, here’s how I’ve over the last 30k miles kept my’n looking and working factory fresh. All of this is – my way, so do as you do and wear safety glasses and rubber gloves, read this all the way through and then decide if you’d like to give it a try – then do so at your own risk… Right, let’s get stuck in!


First off, the kit you’ll need:

K&N filter cleaning kit – inclining Power Kleen and K&N spray re-oil
Old medium soft washing up brush
Gunk engine degreaser spray
Plastic bowl
Paper towels
Fan heater / Hair dryer
Rubber gloves and safety glasses
about 40 minutes of your time


In the plastic bowel place the K&N Filter down and spray all over, thoroughly soaking the cotton gauze with Power Kleen. Then slowly and gently agitate the solution with the old washing up brush, work it all in, every nook and cranny. Then, go have a cup of coffee as the Power Kleen does it’s stuff just sitting there in the plastic bowel

Right, coffee was good – cos now it’s soak’n time. Open up the Power Kleen bottle and pour about 25ml of the cleaning solution into the plastic bowel along with about 50ml of Spray Gunk. Add hot water to cover and immerse the K&N Filter – now it’s up to you, but I just leave it in there for about 20 mins – I’ve read/heard about all sorts being used at this stage including bleach and household detergents ect…. But, the Gunk engine cleaner is designed for automotive use and does not leave a residue – so it’s ideal for the super cleaning soak stage


It’s time to scrub, be careful to go with the grooves and not to be too aggressive. It’s about cleaning not shredding. The K&N Filter is super tough, but it’s not made of steel, be careful yet efficient. If needed spray on more Power Kleen as you scrub. By now the water should be really oily and filthy


Rinse, repeat, rinse , repeat, rinse, again and again until the water running through is clear enough to see the K&N Filter is clean and free of dirt and contaminates

Drying, this will take a while and you want to be thorough. Loads of paper towels first to get the bulk of the water out, then a fan heater is a great way to ‘blow dry’ the K&N Filter until it’s bone dry. Inside the engine bay it’s very hot, especially on track days – so the K&N Filter is designed to take a lot of heat – but don’t leave it unattended and keep turning and rotating the K&N Filter to ensure it’s both completely dry and not getting too hot in one area. Once it’s dried off, just set it aside to cool of a bit before adding the K&N spray re-oil.


Using the K&N spray re-oil is as with any spray can, lightly coat over and over to build up a good layer. Then let it dry before adding any additional coats. I’ve found that two good coatings and then a gentle pat down with paper towels around the rubber parts of the K&N filter works for the next 10k

Finally inspect the entire K&N filter, for both evenness of the re-oil coating and that’s it’s all bone dry before fitting back on the cars air intake manifold – It should look lipstick red glossy and almost as good as when it was first fitted.

Repeat every 10k miles

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