Air Filter


If you are touring Australia with your 4WD, air filters are a huge issue. You will need to change them all the time. There is no such thing as cleaning an air filter, well, you could give it a bash and knock some of the red dust out of it and that might help a little but that’s not really the kind of dirt and contaminants air filters are really all about filtering out. So what do they really do?


Air filters do 2 very important contradictory jobs. On one hand, you need an air filter that allows good airflow because air is one-third of the combustion equation inside your engine (air, fuel and spark). On the other hand, an air filter must filter out contaminants that damage the engine when passing through with the air and fuel mix as well as reducing the combustibility, and therefore reducing the performance of your engine.


A blocked or dirty air filter reduces airflow leading to engine wear, poor performance, increased emissions and an increase in fuel consumption. It’s not like you can clean an air filter with an air compressor or bang them clean, even if it does appear that you’ve done just that from the amount of gunk you will see. Air filters can only ever be replaced. Nevertheless, a good air filter will get dirty faster and need replacing earlier because it is doing its job of collecting those contaminants better.


This is the catch 22. A good air filter will allow for increased airflow and also filter contaminants way down to the tiniest particles we cannot see. That means that there is a limit to how long it can provide good air flow because as it becomes clogged the airflow is reduced.

Before we continue, let’s get some of the variables for this discussion clear. We are talking about purchasing a replacement air filter for your standard consumer 4WD. It is not a classic or show quality vehicle and it is definitely not a racing/sports vehicle; we are talking about the majority of 4WDs on the market in Australia, either new and still under warranty or vehicles without new-car warranties either still owned by the first owner or those purchased used under 10 years old.


Essentially, there are 4 main types of air filters on the market. Before we get into the types of air filters on the market, you should only purchase an air filter from a reputable dealer, retailer or supplier that can provide you with the following:

• An established reputation
• A guarantee or warranty
• After sales support
• A direct means of recourse

If you are thinking that’s a lot to be fussed about when buying something as minor as an air filter that is readily available online with great pricing, even better than the cheapest you’ve ever seen in-store with fast and free delivery, then you’re about to get a small shock.

I mean, let’s face it, we are only talking about an air filter here and you may need a number of them if you are hitting the dirt roads and soft beaches for 12 weeks over Easter, mid-year school holidays, Christmas and New Year, right? You might need one on the road in a hurry if you get caught in a monster dust storm.

When it comes to replacing your air filter, there are so many available on the market it can be confusing. Let’s take a look at the main types and when they are best suited to your vehicle under our said conditions.


This type of air filter will be the same as the one your car came with. It will come in the same box and have the same logo on it as your car. It will be the most expensive of air filters and many people (like me and you) probably think it was made by your vehicle’s manufacturer. A Genuine replacement air filter will be the most expensive except where a high-performance air filter is more expensive. Note, ‘Genuine’ with a capital ‘G’. I am designating Genuine as a pronoun because we are not merely describing these types of air filters, we are naming/categorising them. In this case, Genuine means the air filter is only available from the vehicle manufacturer and is branded as their part.

Even though there are those that will tell you that Genuine parts are always the best, that is not the case at all. Those who tell you that are making more money by you paying for them over the money they would make if you chose another part. As we go further, you will see Genuine parts are genuinely not the best for all situations.

I’d also make sure if a dealership was using new parts on my car when repairing and servicing on behalf of my vehicle manufacture. Unless you read the fine print, you might not know that most vehicle manufacturers reserve the right to supply used or new parts – unbelievable as it is. Maybe that is their way of trying to convince us that their parts are equally good whether they are new or used but it doesn’t really cut it for me. It’s highly unlikely that would be the case when replacing your air filter, but knowing that small fact is important either way.

Nevertheless, if your car is under warranty and the Genuine parts are included, you’ll be getting a Genuine replacement air filter when your vehicle gets serviced by the dealership and there is no need to think twice about that.


An OEM replacement air filter is one that will directly replace the air filter on your vehicle down to the model. Any air filter sold as an OEM replacement air filter has to meet some very specific guidelines that meet the standards of the vehicle manufacturer to be classed as an OEM air filter. It may even be identical to the Genuine part and made by the exact same company that makes the Genuine air filter for the vehicle manufacturer but doesn’t have the logo of the vehicle manufacturer. At a minimum, an OEM replacement air filter is manufactured to meet the strict requirements of the vehicle manufacturer.

If your vehicle is not under new-car warranty and it is, say, 4-6 years old, you are the second or third owner, there is little reason to pay the cost of a Genuine air filter and an OEM air filter is simply the best option meeting the requirements of the manufacturer at a much better price. It’s normal for OEM air filters (and all OEM parts) to be around 1/2-1/3 the price of the Genuine part.

OEM stands for Original Equipment Manufacturer. This part was built by a company that makes the Genuine parts the for the vehicle manufacturer. It’s not rare to compare the matching Genuine replacement part and the matching OEM replacement part for a particular vehicle and find much that differentiates the parts, except the box they came in. They may and often have the exact same part numbers.

In summary, other than a huge difference in price, the only difference between the Genuine air filter and the OEM air filter for your car is probably the logo on the box, and the logo on the filter if there is one.

Nevertheless, I would only buy an OEM replacement air filter from a reputable auto parts supplier.


Aftermarket car parts are also known as “generic”. This third category of replacement parts, and in our case air filters, is also often misunderstood. Let’s break down some undeniable facts and work with that.

First of all, to make aftermarket parts, the aftermarket replacement part manufacturer has to pay rights in order to produce them. That is a levy per part made paid to the vehicle manufacturer. Another interesting point about some aftermarket parts is the fact they demonstrate better performance than the Genuine and OEM parts ever did. Some aftermarket parts producers are very specialised and they look for weaknesses in the Genuine and OEM parts that can be improved on.

If your 4WD is more than 4-6 years old, an official aftermarket part is going to be the better choice. There is a good chance it will perform better than the now old Genuine or OEM air filter, plus it will still be much cheaper.

Ultimately, the vehicle manufacturer can reduce its costs and increase the life of its vehicles on the road while maintaining vehicle value in the market by having “official” aftermarket parts on the market. Those parts may often be made of materials that cost less but still perform sufficiently or better.

The aftermarket industry is extremely important for vehicle manufacturers as those manufacturers provide a solution for maintaining and supplying the manufacturer’s vehicles with parts many years down the track. This gives the vehicles extra longevity and a better resale value. Aftermarket parts manufacturers are often very nimble and can respond to the needs of the market faster than the behemoths of the motor vehicle industry. If the major car manufacturers didn’t have aftermarket parts makers, they would struggle to keep their vehicles on the road. Big brand names need to keep moving forward and improving their vehicles, so the aftermarket part producer and supplier is doing the brand manufacturer a favour, while often wrongly getting bashed for being cheap and nasty.

Again, I would only buy an aftermarket air filter from a reputable auto parts and service supplier. To summarise, if you have a vehicle that is over 6 years old, go with an official aftermarket air filter. It will be cheaper again and do a great job.


We all want extra performance but that extra performance could come at a price if you choose without understanding the full ramifications of your actions. And that’s easy to do when you aren’t an expert or you listen to the advice of someone who doesn’t really know what they are talking about or a product’s marketing gets the better of you.

For example, a high-performance air filter could allow a huge amount of airflow by simply not doing a good job of filtering out as much of the contaminants that is generally required. That’s fine if you are serious into touring or racing and regularly rebuilding your engine. I see “high-performance” written on just about everything when looking at replacement parts for my 4WD.

This is where, someone like me, your regular Joe, can make the wrong choice thinking that we are going to get a whole lot of extra performance out of our standard factory 4WD with a random air filter claiming high-performance. In fact, that air filter might be, and probably will be, giving you some extra performance at the cost of your engine.

On the other hand, a true high-performance air filter is made or modified by an established high-performance company, brand or professional. All of their high-performance parts, even air filters come with a knowledge requirement on behalf of the purchaser. In other words, you need to know or have someone who knows the full impact of any part, including a high-performance air filter. For example, a particular high-performance air filter on a particular 4WD will result in another extra 30% performance if the ECU is tweaked it the right way. Unless you are getting the whole engine-tune package from a specialist, stay well clear of high-performance air filters, no matter where they are from.

High-performance replacement air filters are way down the bottom of what some of the top high-performance specialists do in their performance packages, and they wouldn’t just do the high-performance air filter alone.


This is one issue we must discuss for new car owners and car owners with vehicles under warranty. Technically speaking under Australian consumer law, probably won’t void your new car warranty just because you did not use Genuine replacement parts but you could void the warranty on that part, and so on. That being said, you will void the faith between you and your dealership if you are not using a Genuine air filter.


If you are touring Australia, you need to look at the type of terrain you will cover and consider that. The best thing is to stock up on a couple of OEM or aftermarket air filters unless your vehicle is under warranty. If your vehicle is under warranty then Genuine air filters are probably included in the deal as a part of your vehicle’s servicing – talk to your dealership and see what deal they can do before you head out because air filters are not the limit of extras anyone should be taking with them as they tour dirty distances around Australia.

Having basic replacements, including a couple of air filters is a must. You will have to make the decision to what you will need, so getting professional advice is a good idea. With a daily driven about town or suburban, air filters are not so much of an issue in Australia. If your vehicle manufacturer recommends changing the air filter every 20,000km, that should be understood as the upper limit for driving on sealed roads close to home and to and from work.

Signs your air filter is dirty start with a reduction in engine performance, mileage to overheating and so on. These are hassles you really don’t need when you are out in the middle of nowhere, especially when the simple change of an air filter could be the difference of being stuck by the side of the dirt road again or well on your way in comfort.

When you are hitting the outback, everything changes and the importance of air filters takes on a whole new dimension. Even if one air filter is relatively affordable, when you need 3-5, the price starts to add up. You need to buy right.


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Mike G
Mike G

Mike loves to travel on the open road, he's really into vehicles of any kind, especially those with 2 wheels.