I'm taking some time to do some equipment maintenance and just took the air filter out of my fairly new Husky 323L trimmer for the first time and I was surprised to see that it only uses a tiny little foam filter. I have always been told by mechanics that a good air filtration system is the key to longevity in an engine. Is this thing really adequate? Also, the manual says to oil it if used in dusty conditions, which I don't really feel mine is. Should I just oil it anyway? It felt kind of oily but that could just be from use I suppose. Thanks.