This product works although it is very difficult to coat the air filter completely. The can dispenses a very narrow stream. If the stream was broad it would be much easier to use. Because of this you have to use more of the product and the can doesn't last as long as other brands. Again, if it coated the filter more completely it would remove more oil from the filter but it doesn't. Lots of oil is left over in the filter after one round of cleaning.
The Klotz foam filter cleaner does an effecctive job at removing dirt and grime from air filters, but if you use it in the basement, it will make your whole house smell of kerosene for a week. I recommend it if you are cleaning filters outdoors.
TECH NOTE: Warning on the front of the can reads, "DANGER: Vapor Harmful. Poison. Direct inhalation of spray may be harmful." Use in a well ventilated area.
It did work very well, but you could honestly probably save a few bucks and use the Gunk engine degreaser instead; or kerosene. I sprayed it on, let it soak for a few, then rinsed it off and let the filter dry. It did clean the filter quite well.