it wont matter. it wasn't the filter for me. the mildew and mold grows throughout the ducting. I (based on stuff I found on other forums) opened the doors, windows down, put towels in front of all vents/AC exits, turned the AC on high (set to the vents, not floor) and removed the filter, ran it for 20-30 seconds then slowly but surely emptied the whole can of Lysol (choose the most mildly or non-scented smell possible--non scented is avail at medical supply places, I used vanilla and it worked without making the car smell) into the filter area..the duct goes up and then down, so I tried my best to get as much mist into the stream of air as possible. Ran the AC like this for a little ewhile, then once the can was tapped out (it was a big can so took awhile) turned the AC off and ran the blower for awhile...make sure recirc isn't on.
I never had problems until my temp sensor went out in the AC so they had to replace the entire AC box...after that it started wreaking terribly...so I did this, and now 95% of th etime I run the blower on high without AC on before I park it for the day for about 30 sec to 1 min and it has kept me clear.
There is a very very subtle lingering vanilla smell, but really, it I doubt anyone else knows it is there.
The filter had nothing to do with it, though when I did swap it t 15k it was filthy