It's been two weeks now since the Technology & Maintenance Council (TMC) Annual Meeting & Expo in Orlando, and I'm still processing the information I gathered from technical sessions, fleet forums and private conversations. There was one topic in particular that came up several times during the week, but, while a lot of people wanted to talk about it, just as many people did not want to talk about it, and probably will not want to talk about it for a long time. The topic? Diesel Particulate Filters (DPF). When will they need to be removed from trucks for cleaning, and who will be responsible for cleaning them? Can they really go 250,000 miles before cleaning, as the engine OEMs claim? If you overshoot the mark, what can go wrong, and who's to blame if it does? Who is going to own the cleaning machines, and how much will it cost to use them? Perhaps the most telling comment came from a fleet maintenance manager who said that where DPF cleaning is concerned, "We're not really sure what 'clean' is." Lots of questions, and no answers. One interesting conversation centered around the idea of a DPF exchange program, in which you could bring your dirty DPF into an authorized cleaning center--your dealer, perhaps--turn it in and get a clean filter in exchange. In a way, it could make life easier for fleets, especially if the cleaning service has pick-up and drop-off service, but wouldn't you always wonder where that "new" DPF has been? I mean, maintenance manages are just like everybody else--I don't know many of them who would be comfortable taking a filter from someone else's truck, without having any idea how that truck was maintained, and putting it on their own vehicle. How would you feel about that?