I know it's been beat to death, but I ignored the discussion for awhile. I finally looked on the very helpful PQIA site where one can easily read all of the VOAs on HD oil. I have since abandoned Travellers and move to Motocraft 15w-40 for my 5k mile OCIs. The numbers don't lie, and being the nature of the 7.3,it definitely idles with a little less injector cackle and I have confidence in the level of protection for my 380k mile engine. I'll get a UOA here in the next 1000 miles when I change over to Fumoto valve.