Yeah, that is my problem with them too. That is why I now exclusively use the correct but non-oilbath filter. These are 1950ish original and start off life looking like this:

http://devestechnet.com/Images/Projects/AirFilter/dryfilter8lg.jpg

and then using a NAPA filter, end up looking like this:

http://devestechnet.com/Images/Projects/AirFilter/dryfilter1lg.jpg

there is even a how-to on this issue here:

http://devestechnet.com/Home/AirFilter

I would love to see someone write a conversion on how to convert an oil bath to a dry filter using the oil bath cannister.

Deve

1950 Chevy 3100 Deluxe Cab
1950 Chevy 3100 Standard Cab
In the Stovebolt Gallery
The Think Tank
More info and tips at Deve's Technet