What is the best oil to use on the Uni or Twin air air filter?  Does k&n oil work?

[2015 Z Force 800 53/Trail EPS]

What is the best oil to use on the Uni or Twin air air filter?  Does k&n oil work?

No,K&N oil is just oil for gauze material. Don't use it for foam filters..completely different media. Use any quality foam filter-specific oil which has a transporter to move it through and leave a sticky resin-based product throughout all the open cells in that foam material. There are many. The best..and hardest to clean is said to be BelRay. The makers of Unifilter make a good oil and cleaner for their filters. Many including myself use FAB-1 treatment and their cleaner. I find it stays put, works very well, cleans easy with their cleaner and doesn't migrate downward or aspirate to get all over the air temp or mass airflow sensors like some others.

K&N oil is sewing machine oil with pretty wine coloured dye added. I'd get a real filter and real reputable foam filter oil. 
And if like me, for some reason you have a bottle of K'n'N oil on your shelf, hey sewing machines need oil too.