AGHHH! Ok there it is all out now. I used a Wix filter set contrary to what was posted on this site. I understand that the filter I have does not meet Ford/Navistar spec. Somebody please tell me they will be fine until the next interval or even half of that I'd be happy with. They were $65. I did not check prior to purchase because the hard drive in my notebook failed and I could have sworn to reading about the quality of Wix filters here. Guess not huh?