I just picked up an hpi air filter for the Tsunami. Are you suppose to oil the outside filter as well? It seems more like a foam sleeve over the filter,and did not seem to be oiled when bought, but the inner filter was defenately oiled.

I dunno that filter but if the inner filter had oil then I'd say your safe.

I ussually oil them both, you can never have too much protection and the outside one being oiled is one more layer of protection to prefilter the dust. Other wise it's ok to leave it the way it is if you want to.

if you are runing in a dusty aria just oil the inside one, the frist one acts like a pre filter and lets you run for longer

yes just oil the inside one. The outside is the prefilter.

I with Allaboutfunhobbies on this one. Oiling both will give you that extra protection.

yeah it does offer more protection. but if your in dusty areas, it will attract more dirt because of the oil. i did that with my bb and the filter would be unreal filthy at a half tank in(even good conditions). all though the dirt NEVER made it to the second filter. what i did was lightly coat th outer one and put good amount on the inner one.its opinion. i dont know better safe then sorry. even more so when all it takes is one grain of dirt to trash your motor. im using an hpi motor in my truck, and i prefer the hpi filter over the stock one from redcat.

Holy crap, I thought you just oil the pre-filter and leave the inner foam filter alone...So I should be oiling BOTH then?

It kind of boils down to preference I think, just like most stuff in the Hobby, but I would with out a doubt Oil the inner filter, the outter prefilter is more or less up to you, but if you do oil the outter filter be aware that it will collect dust and dirt faster and starve the engine of oxygen faster.