What Happens If I Don’t Oil My Air Filter?

So you installed a performance air filter on your car and you heard that it needs to be oiled. Wait, what? What does oil have to do with my air filter? What happens if I don’t oil it? A lot of questions there buddy 🙂 Let’s go through it one by one. 

As always – for a quick answer, oil is used in a performance air filter to trap dust particles and other air impurities from entering your car engine. Without re-oiling, the air impurities could easily enter your engine and cause problems. At the least, these impurities accumulate on your engine and cause wear and tear damages to your pistons and valves. At the worst, you could have an engine failure because your turbochargers or superchargers broke while trying to compress air with impurities on it.

Now the short and quick answer is out of the way – let’s get into the details.

To deliver power, your car needs to ignite fuel and create combustion. This combustion absorbs oxygen. With more oxygen, more fuel can be ignited – resulting in a bigger combustion and more power. 

Your car receives oxygen by sucking in the surrounding air. Oftentimes the air is not clean – consisting of dust particles, insects and other impurities. This is where an air filter comes in – it prevents impurities in the air to enter the car engine. 

It is very important that these impurities get filtered. Otherwise they can enter the engine internals and cause damages – wear and tear damages at the least, total engine failure at the worst. 

It becomes complicated because more performance requires more oxygen. If your air filter is too restrictive, both air and its impurities cannot enter – resulting in a poor performance (because the lack of oxygen!). On the other hand, if your air filter is too loose, too much air impurities can enter the engine – resulting in a great performance but also the risks from too much impurities. We will come back to this point later.

Paper-Based Air Filter

This is usually the stock air filter in many cars. They are made of special-grade paper that are effective in trapping air impurities. They are cheap and easy to replace. Paper-based air filters are not reusable – meaning, once it gets dirty, you have to replace it. Not to worry – they are cheap and can be found in almost every mechanic shop. A lot of car enthusiasts believe that paper-based air filters are too restrictive, which hinder the real capabilities of their engines.

Form Air Filter

Foam air filter includes an additional layer of foam in front of the air filter. This means to enter the engine, air needs to pass through the foam and then the actual filter. Foam air filters are extremely restrictive – capable of trapping all the impurities in the air at the cost of engine performance. Form air filters are suitable when driving on extremely dusty areas. Think off-roading or vehicles in factories.

Performance Air Filter

As the name suggests, a performance air filter is designed to increase car performance in mind. They work by allowing more air to enter the engine. Thus, creating bigger combustion for more power. To achieve this, performance air filters are usually less restrictive, with bigger pores – allowing much more air to enter the engine. 

Performance air filters can cost much more than paper-based air filters. However performance air filters are reusable. You only need to clean and re-oil them every 50,000 to 100,000 miles. Crazy long lasting huh?

Like I just mentioned, performance air filters have bigger pores to allow more air flow for an increased performance. To ensure a clean air flow, performance air filters are oiled. This oil works as a second line of defense to trap the impurities from entering. Performance air filters are the only type that use oil – the others are restrictive enough to trap the impurities.

If you don’t re-oil your performance filter, air impurities are bound to enter your engine. There are two scenarios of this happening: 

• Too much dust particles get stuck in the oil – preventing it to hold further. This means additional dust particles or air impurities will not be filtered by the air filter. Allowing them to go inside your engine internals and cause havoc. 
• The oil in the performance filter is all dried up – providing much less filtration. Any fine particles can easily enter the engine. This only happens if you have been driving with a performance air filter for too long, without re-oiling it. 

All the while, I have been only mentioning dust particles and air ‘impurities’. But what exactly are they? Well, air ‘impurities’ could be road debris, sand and bugs. Knowing this, let’s discuss what happens to your engine if they manage to get inside the engine.

Wear And Tear Damages

At the best case scenario, only wear and tear damages happen. These impurities enter your car engine and accumulate on the valves, pistons and combustion chamber – causing internal scratches and minor damages. With more accumulated impurities, the pistons and valves could get jammed and reduce the performance and fuel efficiency of your car. 

Bad Oxygen Sensor

Without going into too much detail, an oxygen sensor is required to tell the car’s computer exactly how much fuel should be injected into the combustion chamber. If there’s too much oxygen in the exhaust gases, that means your car can inject more fuel to generate bigger combustion and vice versa. This is extremely important for a car to deliver optimal performance and fuel efficiency.

An oxygen sensor could easily get damaged by air impurities. At best – the oxygen sensor becomes less sensitive. At worst – the oxygen sensor totally fails, forcing your car to always inject the same amount of fuel into the combustion chamber. Regardless if it’s too much or too little. I cover more about oxygen sensors in this article if you are interested. 

Engine Failure

This is an extreme condition that could only happen on turbocharged or supercharged cars. Again, without going into too much details, turbochargers and superchargers deliver power by compressing surrounding air and delivering it directly into the combustion chamber. This means, the amount of available air is increased – which means bigger combustion could be generated. 

If air impurities exist during air compression, the turbochargers or superchargers will totally fail to work. This means dangerous failures that could cost a fortune to fix them. Pay more attention to your air filters if you are running turbocharges or superchargers! This is especially important for turbocharged users because a lot of car manufacturers include them as stock parts in your cars. If you are interested in turbochargers and superchargers, I cover them here.

Other dry air filters like the form air filters are easy to clean – simply rinse them with water and let dry. Performance air filters though, are a little different and require more effort and expense. 

To clean oil-based performance air filters, you need to purchase a spray cleaner and the filter oil. Both products should be sold by the manufacturers that sell the performance air filters. Here are the steps to clean:

1. Spray the air filter cleaner on your performance air filter and let it sit for ten minutes. This is done to loosen the dirt that is trapped in the performance air filter. 
2. Before the spray is dry, rinse the performance air filter with low pressure water. Get off all the dirt and repeat step 1 and 2 if necessary
3. After rinsing is done, let the performance air filter to dry naturally.
4. Apply the air filter oil evenly throughout the air filter and let it sit for 20 minutes

If you are a visual person, here’s a video showing you how to clean it instead 🙂 

I suggest you use the cleaners and oil from the same manufacturers of your performance air filter. Each brand of performance air filter is slightly different from each other. It goes without saying that each brand’s cleaner and oil products are designed to work best with its own air filter. To have the best performance, stick with the same brand. For example, if your performance air filter is K&N, then purchase K&N’s cleaner and oil.

If you are thinking of skipping on the oil, then don’t. Just read back on all the consequences we covered above 🙂 . If you are thinking of using other oil like engine oil – also don’t. Engine oils or any other oils are not designed to work as impurities filtration. They might have other side effects that we won’t know.