Learn six misconceptions and outright misinformation about air filters that we reckon need to be addressed.
Fun fact: air, unlike fuel or oil, is the only thing that’s an integral part of your engine’s combustion cycle and reliability that is not required to meet any sort of quality standard.
Think about that for a sec. If you put watery-diesel in your tank you’re going to have problems, so they make rules surrounding fuel quality. If you put crappy oil in your engine that couldn’t lubricate a gate hinge, then your engine will likely go bang. So, again, they came up with a set of quality controls to ensure you’re getting what you pay for. But the air that’s mixed with your fuel in order to turn your crank and provide your vehicle with motive power? That can be as dusty, foul and as low quality as it gets and nobody bats an eye.
Which is weird, but whatever. It also highlights the fact that your air filter has an incredibly important job in terms of making sure your powerplant stays healthy and makes reliable power. You wouldn’t hold a greasy rag up to your mouth in order to help you breathe, would you? And yet so many people have no problems with doing the same to their engines and then expecting them to run at peak efficiency day in and day out.

Anyway, air filters probably don’t get the recognition they deserve, and because we live in the internet age where everybody gets an opinion, there are more misconceptions and outright misinformation flying around than ever before. Here are six of the most often repeated ones that we reckon need to be addressed.
1. All air filters are made of the same stuff
You’ve read or heard this before. Old mate reckons all air filters are fundamentally the same and you can easily save a few bucks by buying the papier-mâché-looking bad boy that has a shoelace for a seal and call it good.
Yeah, nah. Modern filters have to keep up with the finer tolerances and increased complexity of modern diesels (and petrols) while also treading the fine line between flow, service life and adequate filtration to handle Australia’s harsh conditions. Media selection is paramount in air filter development, and techniques like layering and utilising dry and synthetic media are incorporated in filter construction. It’s full on “lots of people in lab coats doing smart stuff” level of science.
2. OE Filters are always the best filters
We still know older-generation farmers who flat-out refuse to use anything but OE filters on their farm-utes, but these days, they’re doing themselves a disservice. Ryco, for example, has built Australia’s only dedicated filtration laboratory to meet and exceed the manufacturer’s performance requirements.
Through the life of the filter, the more dust it catches the less airflow it inherently allows through the media. By rigorously testing each filter on the flow bench, Ryco maximises the durability of the product while retaining peak flow for better engine performance and eliminating dirty air by-pass. As such, you get a better filter, often for less money and with greater nationwide accessibility.

3. Air Filters don’t affect performance
In a perfect world (for your engine at least), we’d all drive around in hermitically sealed chambers that would do away with the need for an air filter altogether. In the real world, we live in a country that’s air is smoggy, dusty and occasionally even chock-full of insects just begging to be kamikazed into a turbocharger.
Now, a poor quality air filter will simply not be able to keep up with those demands, and sooner rather than later, let harmful contaminants through the intake and on into the engine. Basically, a quality air filter will not only offer better protection but also allow your engine’s performance to be maximised for longer periods of time.
4. Only change them according to service intervals
It doesn’t take a rocket surgeon to realise that 10,000km of city driving and 10,000km of dirt roads and mud puddles are not the same thing. Just ask any 4WD mechanic, they’ll tell you that at the 10,000km service interval of a modern turbo-diesel, the air filter may not need changing if it’s only been taken on runs to the shops and the occasional highway trip up the coast. But if that same vehicle gets used regularly off-road and drives in otherwise demanding conditions, then the air filter will not only need changing every 10K, but quite likely more often than that.
If you’re doing a big trip to the Top End, desert, or anywhere remote, checking the filter and replacing it as needed really should be one of the first things to check on the daily.

5. A clean-out is as good as a replacement
Let’s say you do pop the airbox lid off and pluck out the air filter to find it’s caked with bulldust and yesterday’s mudhole exploration. Give it a bang against the boot-sole or blow it out with the compressor and call it good, right?
Nup, this can actually damage the air filter’s structure and you’ll be left off in a worse position than you started, for the few bucks a new filter costs, you’d be mad to be a regular off-road driver and not carry a spare or two. Think of the air filter as your lungs. Would you rather them be breathing clean, fresh air or punching a pack of darts while working in the asbestos mine without a mask?
If you answered the latter, is… is everything ok at home?
6. High-flow air filters work well in off-road vehicles
High-flow air filters are designed to let in the maximum amount of air possible so you can get a bee’s dick more power and are sold under the specious tagline of “allowing your engine to breathe” or something similar that was dreamed up by some sales rep who can’t drive manual and has no idea how an engine works.
Look, for track vehicles and road-based performance cars they work fine. But more flow almost always equates to less filtration. Go back to your local 4X4 mechanic and ask them if they rate high-flow filters for off-road vehicles. Spoiler alert, they won’t.
If you like a dusty intake and drastically shortening your engine life then slap one of those go-fast-red filters in, tell your mates it’s basically a trophy truck now and keep reaching for that rainbow, champion. If you prefer reliability and remote-travel-capability they stick to a quality aftermarket filter that, you know, actually filters.

Shoutout
Massive thanks to the team at Ryco for their help with this article. With one of Australia’s largest vehicle ranges and the entire product line searchable by VIN or Rego, you can hop on over to their website and find the right filters for your 4X4.