Oiling K&N air filter?

Hi guys
A bloke at work has a Suzuki GSx and we sometimes help each other out with bits of maintenance... The K&N on his bike has never been oiled and he's not sure of the procedure, type of oil etc. 

Anyone got any experience of these? (Know it's a different bike but I guess the job is the same). 

I told the bloke at work "if anyone knows, these guys will".

Cheers

Hi Mal, This is the stuff he should be using after it has been cleaned.
http://www.ebay.co.uk/itm/K-N-Filters-Cat-Motorcycle-Air-Filter-Oil-Treatment-/141167241917?pt=UK_Car_Parts_Vehicles_Automobila_ET&var=&hash=item20de392abd

for reference on the recommendations towards his filter, use this guide from K&N Filters
http://www.knfilters.com/faq.htm#17

excellent work - cheers sim