I have been using it for about 10,000 miles based on the 32 page thread in the 6.0 section. I was not having any problems, but just trying to extend the life of the engine. I do know that the combination of AR6200 and AR9100 has improved my fuel mileage. I got 12.5 mpg towing a 10K fifth wheel across country and back.Has anyone used the AR9100 in their 6.7
I'm curious as to if there are any observable results from adding the AR9100?