It's been fairly well documented that nothing should be sprayed into the intake of an EcoBoost engine to clean the carbon. It's a turbo-killer method of dealing with carbon. On the 4-cylinder Eco, which initially had some carbon issues between cylinders 2 and 3, spraying a carbon cleaner killed the turbo almost immediately. On the 3.5, sometimes you'll get away with it, and sometimes you won't. I wonder if what the fleet services guy is doing is contributing to the turbo issues that was initially mentioned. There are even YouTube videos concerning this correlation, so it's easy to get the info and judge it for yourself.