At first it just foamed up. but after squeezing and churning the filter in the cleaner you can see the difference. When done my filter looked clean and no visible dirt or oil was left. I couldn't believe how clean my filter got. will definately use and buy again. You can get about 2 cleanings per bottle.
I love just about all Motorex products but this one is just OK. I have used it just 5 times and it is spent. Used my own bucket and followed directions. After application I still had to use Simple green to really get the filter clean. Yes, i am reeeally picky.
I can't believe how well this cleans filters. I have used it a few times and every time my filter comes out looking like it did the day I bought it. No effort at all. Makes cleaning filters a much less of a pain.