Originally Posted by ExcursionDiesel
Anyone driving 40k/yr is probably 90%+ highway and the 10k oil change interval for the required synthetic is not an issue.
That's what I've thought as well.
You might notice that my check engine light came on this week and the dealer said it was due to a poorly installed air filter 10k ago. I remember having a bit of a time getting the housing to close properly so it certainly could be that I screwed up there. Then I saw the thread where you and others were discussing poorly designed air filters that come apart around the edges.
Anyway it might be a good idea to check those air filters to make sure it's not coming apart on you.