Here is my Fram Tough Guard Air filter that was in my 2008 Suburban since June. I picked up quite a bit of forest fire ash but can still use it again next summer. All the ash turned darker as it picked up a bit of oil that came from the pre-oiled filter material. Same with any material such as insects. It turned darker than normal. No issues. The 6.0 liter engine ran fine. These filters contain no where near the level of oil as K&N air filters.
Last edited by Snagglefoot; 01/12/19 07:37 PM.