Oiled versus Dry Air Filters: What's The Difference? Which is better?

Oiled versus Dry Air Filters: What's The Difference? Which is better?

Usually, an intake is one of the first ideas that come to mind when someone starts modifying a car. Intakes are a relatively cheap, power-producing part (on most applications) and the results can usually be immediately felt and heard, especially on turbocharged applications. If you have been following this engineering blog, you may have noticed that I have been the guy writing about our performance intake development for the past year. This means that I field a lot of questions from our community about intake performance. One of the most common questions, and a topic that is still hotly debated amongst us gearheads, is whether one should use a dry or oiled filter. There is no hard-set answer to that. It depends on a few things, so let's quickly talk about it.

Dry Filters

We all know what a dry filter looks like. Almost all factory cars come with one and they are usually made with either a paper or foam element. Due to this, their filtration properties are generally hard to beat.

Stock intake for the 2016 ND Mazda Miata
Stock intake for the 2016 ND Mazda Miata
Stock intake for the 2016 Honda Civic 1.5T
Stock intake for the 2016 Honda Civic 1.5T
Stock intake for the 2015 Ford Mustang GT
Stock intake for the 2015 Ford Mustang GT

Air intake filters must meet minimum filtration standards and trap a certain amount of air contaminants to prevent harm to the engine, so by OEM design, they are more restrictive with respect to airflow. Although these types of air filters are great at keeping contaminants at bay, over time, the accumulating dirt and trapped particles causes an extreme decrease in power and fuel economy. These filters are already restrictive to begin with, so when you add a layer of dirt to the mix, it's almost like trying to breathe through a paper lunch bag inside another paper lunch bag. Try it! Tough, right?

Stock air filter for the 2016 Ford Focus RS
Stock air filter for the 2016 Ford Focus RS

Due to their materials and construction, the air flow of even the high-performance dry air filters will usually be less than an oiled filter of the same size. The upside to dry filters is that they require less maintenance. They aren't always reusable, since using water to clean them will damage the filter element. Their life can be extended by using compressed air to blow some of the dirt off, but that can only be done so many times. OEM dry filters are generally effective up until 10,000 to 15,000 miles (check your service manual), then they must be replaced. Dry filters are commonly used in vehicles that are driven in drier, dustier climates, where airborne contaminants are way more plentiful than in wetter climates. Many people run dry filters in these environments because there is usually so much dust, that an oiled filter would need to be cleaned constantly. So, in what situations would an oiled filter perform better and how do they differ from dry filters?

Oiled Filters

In most aftermarket intake kits, companies supply their product with an oiled filter. Oiled filters flow more air through their media because they are constructed from a more open cotton material that is coated with a thin layer of oil.

Generally, high-performance dry filters can catch up to 99% of the incoming contaminants due to the smaller micron size of the filter media, while oiled filters catch about 98% of what passes through - a minute difference, but a difference none-the-less.

Big vs small!
Big vs small!

The oiled filter material relies on the tackiness of the oil to catch contaminants while the more open media allows a higher flow rate. The oil acts as a sticky trap for incoming air contaminants, providing an important layer of protection to keep the air free of debris. These filters typically come pre-oiled with a specific amount so they can drop right in without the user having to do anything. Oiled filters are what you see in most race applications (excluding off-road). They aren't always conical as pictured above. Many companies offer a direct drop in replacement for the stock air filter, and often, there is a slight bump in performance.

Another benefit is that these filters can last a lot longer than their dry counterparts. Oiled filters have the advantage of being completely washable and reusable, so you don't have to keep buying filters once they become too dirty. All you must do is follow the instructions to clean the filter and you're all set!

Inside the Mishimoto airbox for the VW MK7

Prototype intake 2015 WRX intake pipe with a brand new Mishimoto filter

However, with greater airflow from these filters comes great responsibility. Oiled filters must be regularly cleaned, maintained and properly oiled, or else they can become detrimental to performance. You may have also heard that oiled filters can damage your mass airflow sensor (MAF). Let's nip this right in the bud. Usually the only way for something like this to happen is if you over-oil your filter when re-applying the oil. If there is too much oil on the filter, some of it can get sucked in through the cotton gauze and damage the MAF sensor. This is where you must be careful and follow the instructions on how to clean your oiled filter.
Check out our Mishimoto Powerstack Performance Air Filter
If properly maintained, an oiled filter can look as new as the day you purchased it. This additional maintenance schedule would be a drawback for some, but for us gearheads, it's just another day under the hood.
The giant five-inch filter for our 2016 Chevy Camaro SS intake!
The giant five-inch filter for our 2016 Chevy Camaro SS intake!

There are benefits to both types of air filters. If you are looking for performance, but are not interested in being bothered with maintenance, a high performance dry filter might be right for you. If you want slightly more airflow and are prepared to properly maintain it, an oiled filter would be a great choice. 

The difference in real-world performance between a dry and oiled filter can sometimes be very small, but what it comes down to is the type of driver you are, and the type of environment you are driving in. When you're trying to shave the 1/100 of a second off your lap time, every ounce of power helps.

OVERVIEW OF THE DIFFERENT TYPES OF CAR AIR FILTERS

Car air filters play a vital role in ensuring that its engine runs smoothly. But with so many air filters on the market, how do you know which one is right for you? 

Two of the most common types of air filters are dry and oiled. Dry air filters are made of a pleated paper material, which traps dirt and debris. 

On the other hand, oiled air filters use cotton gauze material, which is coated with a special oil to trap particles. While both types of filters are effective in keeping your engine clean, the choice ultimately comes down to your driving habits and preferences. 

So the next time you're in the market for a new air filter, consider your options carefully and choose the one that best suits your needs.

ADVANTAGES AND DISADVANTAGES OF AIR FILTERS

When it comes to keeping your car's engine running smoothly, the air filter you choose can make a big difference. Dry air filters, made of paper or cotton fibers, are a popular choice due to their affordability and ease of installation. 

However, they do require regular cleaning and replacement. On the other hand, oiled air filters are made of foam that is saturated with oil, providing superior filtration and improved engine performance. 

But with added expense and the need for frequent re-oiling, they may not be the best option for everyone. Ultimately, the choice between a dry or oiled air filter for your car comes down to your personal preferences and budget.

HOW TO CHOOSE THE RIGHT AIR FILTER

Keeping your car running at its best means taking care of its various systems, including the air filter. This important component stops dirt and debris from entering the engine and causing damage. 

However, with a wide variety of air filters available on the market today, it can be tough to know which one is the right choice for your car. Factors like cost, quality, and compatibility with your vehicle all come into play. 

To simplify your decision-making process, it's important to consider your driving habits, the weather conditions in which you typically drive, and your overall budget. 

With a little bit of knowledge and guidance, you can find the air filter that's best suited to your needs and get your vehicle running smoothly once again.

PROS AND CONS OF REPLACING OR CLEANING AN AIR FILTER

If you're wondering how to keep your car running smoothly, you might consider replacing or cleaning your car's F10 M5 air filter. While these actions can improve your car's performance and fuel efficiency, there are also some downsides to consider. 

On the one hand, replacing a dirty air filter can save you money in the long run by preventing unnecessary wear and tear on your engine. On the other hand, buying a new air filter can be expensive, and cleaning an old one can be time-consuming and messy. 

Ultimately, the decision to replace or clean your car's air filter will depend on your particular needs and circumstances. Take the time to weigh the pros and cons before making a decision.

TIPS FOR REGULARLY MAINTAINING YOUR AIR FILTER

Your car’s air filter is responsible for keeping harmful pollutants and debris from entering your engine and affecting its performance. Regular maintenance of this important component is essential if you want your vehicle to run smoothly and efficiently. 

Fortunately, there are a few simple tips you can follow to keep your air filter working at its best. First, make sure to check it regularly, especially if you drive in dusty or dirty conditions. 

If your filter looks dirty, it’s time to clean or replace it. Additionally, be sure to follow your vehicle manufacturer’s recommendations for replacing your air filter. 

By keeping your air intake system & air filters clean and well-maintained will help ensure your car runs as smoothly as possible.

TROUBLESHOOTING COMMON ISSUES WITH AIR FILTERS

Taking care of your car's air filter is crucial in keeping your engine running smoothly. However, even with regular maintenance, common issues can still occur. 

One problem that many drivers encounter is a dirty air filter, which can lead to reduced airflow and diminished engine performance. Another issue is a clogged air filter, which can cause serious damage to your engine over time. 

By learning how to troubleshoot these common problems and taking preventative measures, such as replacing your air filter regularly, you can save yourself time, money, and headaches in the long run.

So, if you notice your engine struggling or if you haven't changed your air filter in a while, it's important to take action and address the issue before it becomes a more serious problem.


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