Soooo, oiled, properly maintained filters provide the best filtration in sand... 
I'm just curious cause my 86' will be finished some day and ready for the dunes. I just don't want to put it into the sand unless its very well protected. It's taken me years to get it rebuilt this far. I'm not about to do something that will make it all for nothing.
Yes, that has been my experience whether it is a foam or a K&N filter. Foam air filters and K& N filters operate on two totally different principles and require different cleaning and oiling techniques as well as different filter oils to work the best they can. I have not found the K&N filters to last as long as they are advertised to last. K&N filters are often ruined the first time they are cleaned and few guys oil them properly.
Beware there are some imitation filters that look like K&N filters but they do not use the cotton gauze mesh, they use some type of synthetic gauze mesh.
The filter oil will soak into the cotton gauze but the oil will not soak into the synthetic gauze. The oil does not seem to adhere to each fiber in the synthetic gauze. The oil does seem to stay evenly distributed and provide a sticky surface around each small hole the air passes through.