Remember...only a quality foam filter oil treatment.
I used maxima fab1. That is some nasty stuff. I guess it was worse for me because I was doing three at a time. I had to grind off the ring on the connection between the air filter and air box on the 4 wheelers but the Zforce slide right in.
the plastic connection sucks bro, fair warning. I'll stop beating the dead horse
PJ1 is the best filter oil IMO but the UNI kit works fine and can be had for cheap on amazon.
Always keep a couple Uni's pre-oiled in seperate zip lock bags. When one is dirty, pop a fresh one on and use the bag to bring the dirty filter home to clean.