Home

Which Air Filter to Use

Which air filter should I use? What should I consider when deciding which filter system to use?

  • Poor paper
  • Best paper
  • Foam
  • Cotton/oil gauze
  • Synthetic

Well believe it or not they are all correct in some way or another. They are all correct for different situations. You need to decide which one is right for you and the intended use.

Poor quality paper filter
You see this one mentioned when viewing other filter's statistics claiming how much better they are when compared to a poor quality paper filter. WHERE do you buy a poor quality paper filter? Does it say on the box "Poor Quality"? Are they warranted against quality products? Guess if you were selling the car and had to replace the filter before the sell, then this might be the one for you.

Best Paper
Don't all the paper filter manufactures think they are the best? Let's just call this one "Factory Replacement". If you want to keep your car 100% factory stock then this one may just be for you. If you believe that the original filter is an inexpensive standard issue, will do for now filter, then the odds are you have already changed it.
Pretty much you know that that OE filter is going to fit just like it was made for it and it is probably decent quality. Better than that poor paper filter we keep reading about.

Foam
Foam filters have been around for a long time. They are usually impregnated with a renewable oil source to help filter out the dirt particles. They are not as easy to find as some of the other filter types. Amsoil used to sell a line of foam filters.

Cotton/oil gauze
K&N. Claims 50,000 miles between cleaning, guaranteed for a million miles. Flows more air, when dirty than, others do when almost brand new. Well they are more money than other filters but if you can keep reusing them after cleaning and re-oiling them, then in the end you will save money. K&N Filters Part number is E-0945

It does look like most people are willing to admit that the Gauze/oil filters are able to produce better air flow rates than the paper or foam products, however there have been a number of stories of how the oil will cause problems.

MAF sensors are the number one target of these problems. Supposedly the oil from the filter will migrate to the tiny wires in the MAF sensor and cause incorrect readings. K&N has admitted that an incorrectly over oiled filter could cause this type problem. However there have been numerous MAF sensors being replaced when the air filter was never re-oiled but instead was oiled at the factory. K&N has recently released some video showing how it is impossible for the oil to transfer from the filter to the MAF. I have a couple of problems with their claims though.

  1. Their testing takes place in a nice climate controlled building. I can't remember when the last time my engine was run in a climate controlled comfy building.
  2. I had a FACTORY oiled K&N air filter show running oil down the air box. And it just so happened that several months later I experienced a malfunctioning MAF. (I did not know at the time you could clean them)
  3. If you go out in my garage in the summer time and look at my old oil container, you can see where oil is gathering around the cap. I wonder how that oil, traveled UP the spout, out past the threaded cap and was able to pool on the outside of the oil container?

Synthetic
That leaves us with the Synthetic filter. A lot of people are using synthetic oil and oil filters in their car, why not the air filter? Well probably because right now most of your local auto parts stores do not carry a synthetic air filter. BUT Amsoil is currently selling one.

So there you go, easy right?

©2014 BULLITT Archive: Mustang and Mustang Bullitt are registered trademarks of the Ford Motor Company. All other trademarks are property of their respective owners