They are very good. Not scientific, but I have one in my CVLX that went in with the new air intake setup and 20k miles later its still clean. Almost none of that really fine dust that manages to get by paper filters. I haven't cleaned it yet; Im using a restriction gauge to tell me when it needs cleaning.
They are not Donaldson filters. They may use a Donaldson process under license, but they are not Donaldson filters.
If you want one, you better pick one (or two) up quick. They are no longer making them. All that is left is what is in stock.
I cant give an honest review of it because my annual mileage is so low but i can say after 5 yrs and 15K it shows no material deterioration.
The plumbing on the clean side to the throttle body is still clean and dust free. I would buy it again.
I put one in my sisters car last year, I think it's edging up on 25k miles now. Still looks to be in good condition and getting good air flow. Not sure if its much better than the Wix air filters I normally use.
I refuse to use Wix air filters, tried one once, loads of dust got by the filter pleats, the AC HD filter stopped them, I check the MAF and intake tube each change. If I cant get the Amdoil filter, will stick with the AC HD filter.