You DO need to oil a foam filter, it's the same as a cotton element filter like a K&N. It really depends on whether you want your filter to act as a filter.. The oil is still responsible for trapping and holding dirt, without that the foam isn't going to do that great of a job. The K&N cotton filter kit oil should work fine on the foam, it's just a detergent/emulsifier solution and red high tack oil. I bought a Amsoil foam filter kit from a local dealer and it's pretty much identical to the K&N kits I've had in the past. The Amsoil stuff was cheap, I'll be buying that for ever after for my filter needs. The one nice thing about the K&N kit is aerosol oil, the Amsoil stuff is a little bottle so you can work it into the foam by hand.