I have used Diesel Kleen for years with good results.
But, recently I switched to the Motorcraft diesel fuel conditioner and I am seeing slightly better fuel economy and "seat of the pants" performance gains.
2013 F350 6.7L FX4 Lariat Auto CC LWB- stock
2010 F350 6.4L FX4 Lariat Auto CC SWB- AFE Stage II, Flo Pro 5" TBE, H&S Mini Maxx on Hot Damn/Hot!
02 F250 7.3L 4x4 6spd Lariat CC LWB
3" lift, BFG A/T 315's on stock wheels, AFE stage II, Edge J/A, 4" straight piped, Ranch Hand frt/rear