First - having clean looking oil in a diesel means nothing. In fact, the oil is suppose to suspend soot as part of its formulation. Again - any conclusion on a filters performance is way off base if it is only made on oil color. You WANT your oil to suspend the soot. My oil looks dark quickly. All my oil analysis comes back good for particulates.

There are many documented cases of engine damage due to will-fit oil filters. At $15 a "pop" for the proper filter, what I find amazing is that we are still discussing it and that people are still risking their engine using them.

Documented reasons for the issues with the "will-fit" are not ONLY dimensional, but are also with the materials of construction AND the quality of construction. Now I know someone will say - prove it. To that I will say, I have seen the reports, watched Ford videos on it, talked to techs, seen pics of collapsed will-fit filters, etc. The information is out there and I am convinced (as are the people on 8+ forums that have demonstrated over many years to have the experience and knowledge to be beieved when they say "Stay away from will-fit" filters").

I guess the hardest concept for people is the one about "long-term" damage. Seems that people now days need instant feedback on a decision or they question the recommendation. Now I have seen filters with plastic adapters give people that instant feedback (quick failures and plastic parts getting into the oil system), but other will-fits (that allow bypassing the filter and such) take longer to result in issues.

Regarding the billet caps - I have wondered the same thing. That is why I do not have one. They may be perfectly fine, but I do not know exactly how to be 100% sure.